U.S. patent application number 10/544487 was filed with the patent office on 2007-02-15 for method for manufacturing semi-transparent semi-reflective electrode substrate, reflective element substrate, method for manufacturing same, etching composition used for the method for manufacturing the reflective electrode substrate.
Invention is credited to Kazuyoshi Inoue.
Application Number | 20070037402 10/544487 |
Document ID | / |
Family ID | 32854103 |
Filed Date | 2007-02-15 |
United States Patent
Application |
20070037402 |
Kind Code |
A1 |
Inoue; Kazuyoshi |
February 15, 2007 |
Method for manufacturing semi-transparent semi-reflective electrode
substrate, reflective element substrate, method for manufacturing
same, etching composition used for the method for manufacturing the
reflective electrode substrate
Abstract
An etchant for selective etching is used to simplify the
production process of a semi-transparent semi-reflective electrode
substrate, and temporal loss is not produced by avoiding
troublesome repeated works, thereby efficiently providing a
semi-transparent semi-reflective electrode substrate. A method for
manufacturing a semi-transparent semi-reflective electrode
substrate where a metal oxide layer (12) made of at least indium
oxide and an inorganic compound layer (14) at least made of Al or
Ag are formed in order of mention. The method comprises a step of
etching the inorganic compound layer (14) with an etchant X
composed of phosphoric acid, nitric acid, and acetic acid and a
step of etching the metal oxide layer (12) with an etchant a
containing oxalic acid.
Inventors: |
Inoue; Kazuyoshi; (Chiba,
JP) |
Correspondence
Address: |
C. IRVIN MCCLELLAND;OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
32854103 |
Appl. No.: |
10/544487 |
Filed: |
November 20, 2003 |
PCT Filed: |
November 20, 2003 |
PCT NO: |
PCT/JP03/14810 |
371 Date: |
May 23, 2006 |
Current U.S.
Class: |
438/758 |
Current CPC
Class: |
G02F 1/13439 20130101;
C23F 1/30 20130101; G02F 1/133555 20130101; H01L 51/5218 20130101;
C23F 1/20 20130101; H01L 2251/5315 20130101 |
Class at
Publication: |
438/758 |
International
Class: |
H01L 21/31 20060101
H01L021/31; H01L 21/469 20060101 H01L021/469 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 5, 2003 |
JP |
2003-27999 |
Mar 26, 2003 |
JP |
2003-84905 |
May 8, 2003 |
JP |
2003-129824 |
Claims
1. A method for manufacturing a semi-transparent semi-reflective
electrode substrate in which a metal oxide layer composed of at
least indium oxide and an inorganic compound layer composed of at
least Al or Ag are stacked in order of mention, the method
comprising the steps of: subjecting the inorganic compound layer to
etching with an etchant .lamda. containing phosphoric acid, nitric
acid, and acetic acid; and subjecting the metal oxide layer to
etching with an etchant .sigma. containing oxalic acid.
2. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to claim 1, wherein when the etching
rate of the metal oxide layer with the etchant .lamda. is defined
as A and the etching rate of the inorganic compound layer with the
etchant .lamda. is defined as B, the ratio B/A is 10 or more.
3. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to claim 1 or 2, wherein the etchant
.lamda. contains 30 to 60 wt % of phosphate ions, 1 to 5 wt % of
nitrate ions, and 30 to 50 wt % of acetate ions.
4. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to any one of claims 1 to 3, wherein
the metal oxide layer contains a lanthanoid group metal oxide.
5. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to claim 4, wherein the lanthanoid
group metal oxide contains at least one metal oxide selected from
the group consisting of cerium oxide, praseodymium oxide, neodymium
oxide, samarium oxide, europium oxide, gadolinium oxide, terbium
oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium
oxide, ytterbium oxide, and lutetium oxide.
6. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to claim 4 or 5, wherein the ratio of
the lanthanoid group metal oxide contained in the metal oxide layer
is 0.1 atomic % or more but less than 10 atomic % with respect to
the total metal atoms of the metal oxides.
7. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to any one of claims 1 to 6, wherein
the inorganic compound layer contains 0.1 to 3 wt % of at least one
metal selected from among Au, Pt, and Nd.
8. A method for manufacturing a semi-transparent semi-reflective
electrode substrate in which a first metal oxide layer composed of
at least indium oxide, an inorganic compound layer composed of at
least Al or Ag, and a second metal oxide layer composed of at least
indium oxide or zinc oxide are stacked in order of mention, the
method comprising the steps of: subjecting the second metal oxide
layer and the inorganic compound layer to etching with an etchant
.lamda. containing phosphoric acid, nitric acid, and acetic acid;
and subjecting the first metal oxide layer to etching with an
etchant .sigma. containing oxalic acid.
9. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to claim 8, wherein when the etching
rate of the first metal oxide layer with the etchant .lamda. is
defined as A and the etching rate of the inorganic compound layer
with the etchant .lamda. is defined as B, the ratio B/A is 10 or
more, and wherein when the etching rate of the inorganic compound
layer with the etchant .lamda. is defined as C and the etching rate
of the second metal oxide layer with the etchant .lamda. is defined
as D, the ratio C/D is in the range of 0.5 to 2.0.
10. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to claim 8 or 9, wherein the etchant
.lamda. contains 30 to 60 wt % of phosphate ions, 1 to 5 wt % of
nitrate ions, and 30 to 50 wt % of acetate ions.
11. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to any one of claims 8 to 10, wherein
the first metal oxide layer contains a lanthanoid group metal
oxide.
12. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to claim 11, wherein the lanthanoid
group metal oxide contains at least one metal oxide selected from
the group consisting of cerium oxide, praseodymium oxide, neodymium
oxide, samarium oxide, europium oxide, gadolinium oxide, terbium
oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium
oxide, ytterbium oxide, and lutetium oxide.
13. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to claim 11 or 12, wherein the ratio
of the lanthanoid group metal oxide contained in the metal oxide
layer is 0.1 atomic % or more but less than 10 atomic % with
respect to the total metal atoms of the metal oxides.
14. The method for manufacturing a semi-transparent semi-reflective
electrode substrate according to any one of claims 8 to 13, wherein
the inorganic compound layer contains 0.1 to 3 wt % of at least one
metal selected from among Au, Pt, and Nd.
15. A reflective electrode substrate comprising: a substrate; an
inorganic compound layer composed of at least Al; and a metal oxide
layer composed of at least indium oxide, wherein the inorganic
compound layer and the metal oxide layer are stacked on the
substrate in order of mention.
16. The reflective electrode substrate according to claim 15,
wherein the metal oxide layer contains zinc oxide, and wherein
[In]/([In]+[Zn]) is 0.7 to 0.95 (where [In] and [Zn] represent the
number of indium atoms and the number of zinc atoms in the metal
oxide layer, respectively).
17. The reflective electrode substrate according to claim 15 or 16,
wherein the inorganic compound layer contains 0.1 to 3 wt % of at
least one metal selected from among Au, Pt, and Nd.
18. The reflective electrode substrate according to any one of
claims 15 to 17, wherein the metal oxide layer contains a
lanthanoid group metal oxide.
19. The reflective electrode substrate according to claim 18,
wherein the lanthanoid group metal oxide contains at least one
metal oxide selected from the group consisting of cerium oxide,
praseodymium oxide, neodymium oxide, samarium oxide, europium
oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium
oxide, erbium oxide, thulium oxide, ytterbium oxide, and lutetium
oxide.
20. The reflective electrode substrate according to claim 18 or 19,
wherein the ratio of the lanthanoid group metal oxide contained in
the metal oxide layer is 0.1 to 10 atomic % with respect to the
total metal atoms of the metal oxides.
21. The reflective electrode substrate according to any one of
claims 15 to 20, wherein the work function of the metal oxide layer
is 5.6 eV or more.
22. A method for manufacturing the reflective electrode substrate
according to any one of claims 15 to 21, comprising the step of
subjecting the metal oxide layer and the inorganic compound layer
to batch etching with an etchant containing phosphoric acid, nitric
acid, and acetic acid.
23. The method for manufacturing a reflective electrode substrate
according to claim 22, wherein when the etching rate of the
inorganic compound layer with the etchant is defined as A and the
etching rate of the metal oxide layer with the etchant is defined
as B, the ratio B/A is in the range of 0.5 to 2.0.
24. The method for manufacturing a reflective electrode substrate
according to claim 22 or 23, wherein the etchant contains 30 to 60
wt % of phosphoric acid, 1 to 5 wt % of nitric acid, and 30 to 50
wt % of acetic acid.
25. An etchant to be used for the step of batch etching according
to claim 22, comprising an etching composition containing 30 to 60
wt % of phosphoric acid, 1 to 5 wt % of nitric acid, and 30 to 50
wt % of acetic acid.
26. A reflective electrode substrate comprising: a substrate; an
inorganic compound layer composed of at least Ag; and a metal oxide
layer composed of at least indium oxide and a lanthanoid group
metal oxide, wherein the inorganic compound layer and the metal
oxide layer are stacked on the substrate in order of mention.
27. The reflective electrode substrate according to claim 26,
wherein the lanthanoid group metal oxide contains at least one
metal oxide selected from the group consisting of cerium oxide,
praseodymium oxide, neodymium oxide, samarium oxide, europium
oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium
oxide, erbium oxide, thulium oxide, ytterbium oxide, and lutetium
oxide.
28. The reflective electrode substrate according to claim 26 or 27,
wherein the ratio of the lanthanoid group metal atoms contained in
the metal oxide layer is 0.1 to 20 atomic % with respect to the
total metal atoms of the metal oxides.
29. The reflective electrode substrate according to any one of
claims 26 to 28, wherein the metal oxide layer contains zinc oxide,
and wherein [In]/([In]+[Zn]) is 0.7 to 0.95 (where [In] and [Zn]
represent the number of indium atoms and the number of zinc atoms
in the metal oxide layer, respectively).
30. The reflective electrode substrate according to any one of
claims 26 to 29, wherein [In]/([In]+[Sn]) is 0.7to 0.97 (where [Sn]
represents the number of tin atoms in the metal oxide layer).
31. The reflective electrode substrate according to any one of
claims 26 or 30, wherein the inorganic compound layer contains 0.1
to 3 wt % of at least one metal selected from among Au, Cu, Pd, Zr,
Ni, Co, and Nd.
32. The reflective electrode substrate according to any one of
claims 26 to 31, wherein the work function of the metal oxide layer
is 5.25 eV or more.
33. A method for manufacturing the reflective electrode substrate
according to any one of claims 26 to 32, comprising the steps of:
subjecting the metal oxide layer to etching with an etchant
containing oxalic acid; and subjecting the inorganic compound layer
to etching with an etchant containing phosphoric acid, nitric acid,
and acetic acid.
34. The method for manufacturing a reflective electrode substrate
according to claim 33, wherein the etchant to be used for etching
of the inorganic compound layer contains 30 to 60 wt % of
phosphoric acid, 1 to 5 wt % of nitric acid, and 30 to 50 wt % of
acetic acid.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for manufacturing
a semi-transparent semi-reflective liquid crystal electrode
substrate, and an etchant for use in manufacturing a
semi-transparent semi-reflective electrode substrate. Further, the
present invention relates to a reflective electrode substrate to be
used for reflective liquid crystal devices or light-emitting
devices, a method for manufacturing the same, and an etchant to be
used for the manufacturing method.
BACKGROUND ART
[0002] Related Art 1 (Semi-transparent Semi-Reflective Liquid
Crystal Device)
[0003] Heretofore, semi-transparent semi-reflective liquid crystal
devices have been intensively investigated for the reasons
described below. [0004] (1) Semi-transparent semi-reflective liquid
crystal devices can provide bright displays both in- and outdoors.
[0005] (2) In a case where semi-transparent semi-reflective liquid
crystal devices are used in bright light, they operate as
reflective liquid crystal devices to reduce power consumption.
[0006] (3) Semi-transparent semi-reflective liquid crystal devices
are suitable for portable displays because they consume low amounts
of power. [0007] (4) Semi-transparent semi-reflective liquid
crystal devices can easily provide full color displays.
[0008] However, in the case of such a semi-transparent
semi-reflective liquid crystal device, it is necessary to provide a
reflective electrode and a transparent electrode as electrodes for
driving liquid crystal in one pixel, thus resulting in a
complicated manufacturing process, a low yield, and an increase in
price. In addition, there is also a problem that it is hard for
users to see displays due to the difference in vision between the
transparent mode and the reflective mode. From the viewpoint of the
problem, Japanese Patent Laid-open No. 2002-49034 or 2002-49033 has
disclosed a semi-transparent semi-reflective liquid crystal display
device in which silver reflective films 120 are covered with a
protection film 130, and transparent electrodes for driving liquid
crystal are provided on the protection film 130. Further, the
silver reflective films constituting a silver reflective layer and
the transparent electrodes for driving liquid crystal are arranged
in a staggered format. FIG. 7 is a cross-sectional view which shows
the entire structure of the semi-transparent semi-reflective liquid
crystal display device disclosed in Japanese Patent Laid-open No.
2002-49034 or 2002-49033. In this liquid crystal display device, a
first substrate 100 and a second substrate 110 are provided so as
to be opposed to each other, and a space between the first
substrate 100 and the second substrate 110 is filled with liquid
crystal. As described above, the liquid crystal display device
further includes the silver reflective films 120 provided on the
first substrate 100, the protection film 130 provided on the silver
reflective film 120, the transparent electrodes 140 provided on the
protection film 130, and an orientational film provided on the
transparent electrodes 140. According to such a structure, it is
possible to suppress the growth of crystalline particles
constituting the silver reflective film 120 even when the
orientational film is subjected to high-temperature treatment after
the reflective film is formed, thereby preventing a decrease in
reflectivity.
[0009] Further, Japanese Patent Laid-open No. 2001-305529 has
disclosed a liquid crystal display device using a single
semi-transparent reflective film. In this liquid crystal display
device, an Si thin film having an auxiliary reflection function is
provided below a silver reflection film 120. According to such a
structure, the liquid crystal display device can provide displays
in a preferred color tone while keeping optimum brightness and
contrast in both the transparent mode and reflective mode.
[0010] Related Art 2 (Reflective Liquid Crystal Device)
[0011] Heretofore, reflective liquid crystal displays have been
actively developed for the reasons described below. [0012] (1)
Reflective liquid crystal devices are lightweight and can provide
bright displays. [0013] (2) Reflective liquid crystal devices need
no backlight so that it is possible to save power consumption.
[0014] (3) Reflective liquid crystal devices need little
electricity to work and are therefore suitable for portable
displays.
[0015] Particularly, top emission organic electroluminescence
(hereinafter, electroluminescence is simply referred to as "EL")
devices are receiving attention for the reasons described below.
[0016] (1) EL devices are solid devices and are therefore easy to
handle. [0017] (2) EL devices are self-emission devices and
therefore do not need any other light-emitting elements. [0018] (3)
EL devices are excellent in visibility and are therefore suitable
for displays. [0019] (4) EL devices can easily provide full-color
displays.
[0020] In such a reflective liquid crystal display device,
especially in a top emission organic EL display device, a
reflective electrode is usually used for an electrode layer for
driving. Such a reflective electrode preferably has high
reflectivity from the viewpoint of luminous efficiency of the
organic EL device.
[0021] As a reflective electrode for organic EL devices, a
reflective electrode disclosed in WO 00/065879 can be mentioned by
way of example. The reflective electrode is formed from Mo, Ru, V,
or oxides thereof, and is in contact with an organic material
constituting an organic light-emitting device (OLED).
[0022] Further, Japanese Patent Laid-open No. 2002-216976 has
disclosed an electrode for light-emitting devices. The electrode
has a structure in which a Cr film and a Cr oxide film are
laminated or a structure in which a film formed from a metal such
as Mo, W, Ta, Nb, Ni, or Pt and a film formed from a metal oxide
thereof are laminated.
[0023] On the other hand, it has been known that a reflective
electrode for driving liquid crystal can be formed from, for
example, Al having high reflectivity.
[0024] Related Art 3 (Reflective Liquid Crystal Device)
[0025] As described in Related Art 2, in reflective liquid crystal
display devices, especially in top emission organic EL display
devices, a reflective electrode is usually used for an electrode
layer for driving.
[0026] Japanese Patent Laid-open No. 2003-36037 has reported that
by making the ratio of the thickness of a metal oxide layer formed
from Cr, Ta, W, Ti, Mo, or the like to that of an Ag alloy layer
smaller than the ratio of the etching rate of the metal oxide layer
to that of the Ag alloy layer, it is possible to reduce the height
of a step which may be produced due to etching at the boundary
between the metal oxide layer and the Ag alloy layer.
[0027] On the other hand, it has been known that a reflective
electrode for driving liquid crystal can be formed from, for
example, Ag having high reflectivity.
DISCLOSURE OF THE INVENTION
[0028] First Object (in Relation to Related Art 1)
[0029] According to Japanese Patent Laid-open Nos. 2002-49034 and
2002-49033, a transparent electrode and a reflective electrode are
provided in different layers. Therefore, it is necessary to repeat
the cycle including film formation and etching by means of
photolithography to form these layers, which makes the
manufacturing processes complicated and needs time for transport
between different processes.
[0030] In order to solve such a problem, the present inventors have
intensively investigated, and as a result they have found that it
is possible to simplify the process of film formation-etching by
using a transparent conductive film which can be etched with an
acid not corrosive to metal but has resistance to an etchant for
metal.
[0031] That is, by using an etchant which enables selective
etching, it is possible to avoid a repetition of complicated
operations to simplify the manufacturing processes. It is therefore
a first object of the present invention to provide a
semi-transparent semi-reflective electrode substrate efficiently
without time loss.
[0032] Second Object (in Relation to Related Art 2)
[0033] The above-described reflective electrode formed from Mo, W,
Ta, Nb, Ni, Pt, Ru, V, or Cr has low reflectivity, and therefore
the luminous efficiency of the organic EL device is lowered.
[0034] Particularly, in the case of organic EL devices, such a
reflective electrode is used as anode. Therefore, the reflective
electrode preferably has a high work function from the viewpoint of
luminous efficiency. The work functions of the metals mentioned
above such as Mo are relatively high, but are not sufficiently high
because the ionization potential of an organic compound used is 5.6
to 5.8 eV.
[0035] In a case where Al having high reflectivity is used for a
reflective electrode, Al has a work function of 4.2, but it is not
so high relative to the ionization potential of an organic compound
used.
[0036] From the viewpoint of the problem described above, it is a
second object of the present invention to provide a reflective
electrode substrate having the following properties: (1) low
surface resistivity, (2) excellent reflection characteristic and
durability, and (3) high work function, and a method for
manufacturing such a reflective electrode substrate. The reflective
electrode substrate according to the present invention is
particularly useful as an electrode substrate for top emission
organic EL devices.
[0037] Third Object (in Relation to Related Art 3)
[0038] As described with reference to the second object, the work
functions of the metals mentioned above such as Mo are relatively
high, but are not sufficiently high because the ionization
potential of an organic compound used is 5.6 to 5.8 eV.
[0039] In a case where Ag having high reflectivity is used for a
reflective electrode, Ag has a work function of 4.2, but it is not
so high relative to the ionization potential of an organic compound
used.
[0040] From the viewpoint of the problem described above, it is a
third object of the present invention to provide a reflective
electrode substrate having the following properties: (1) low
surface resistivity, (2) excellent reflection characteristic and
durability, and (3) high work function, and a method for
manufacturing such a reflective electrode substrate. The reflective
electrode substrate according to the present invention is
particularly useful as an electrode substrate for top emission
organic EL devices.
[0041] In order to achieve the above objects, the present invention
takes the following measures.
[0042] First Invention
[0043] First, a first invention for mainly achieving the first
object will be described. It is to be noted that the first
invention will be described later in more detail with reference to
a first embodiment. [0044] 1. According to the present invention,
there is provided a method for manufacturing a semi-transparent
semi-reflective electrode substrate in which a metal oxide layer
composed of at least indium oxide and an inorganic compound layer
composed of at least Al or Ag are stacked in order of mention,
including the steps of:
[0045] subjecting the inorganic compound layer to etching with an
etchant .lamda. containing phosphoric acid, nitric acid, and acetic
acid; and
[0046] subjecting the metal oxide layer to etching with an etchant
.sigma. containing oxalic acid.
[0047] According to a conventional method, it is necessary to
repeat the cycle including film formation and etching by means of
photolithography to form these layers. However, according to the
present invention, it is possible to provide these layers by first
forming films and then subjecting each of the films to etching,
thereby simplifying the manufacturing processes and reducing the
time required for manufacturing the semi-transparent
semi-reflective electrode substrate as compared to the conventional
method.
[0048] The etchant .sigma. containing oxalic acid may contain other
acids such as hydrochloric acid, nitric acid, sulfonic acid, and
disulfonic acid in small amounts as long as the etchant .sigma. do
not cause damage to the inorganic compound layer composed of Ag or
Al. [0049] 2. In the present invention, it is preferred that when
the etching rate of the metal oxide layer with the etchant .lamda.
is defined as A and the etching rate of the inorganic compound
layer with the etchant .lamda. is defined as B, the ratio B/A is 10
or more.
[0050] Here, the word "etching rate ratio" is defined as follows:
Etching rate ratio=Etching rate of inorganic compound layer
composed of Ag or Al/Etching rate of metal oxide layer
[0051] If the etching rate ratio is less than 10, the metal oxide
layer provided below the inorganic compound layer is also etched
when the inorganic compound layer composed of Ag or Al is subjected
to etching, thereby causing damage to the metal oxide layer.
[0052] In general, etching is carried out for a time period about
1.2 to 2.0 times longer than just etching time. Here, the time
period from the initiation of etching to the end of etching is
defined as "just etching time", and the time period when etching is
further carried out over the just etching time is defined as
"over-etching time". In consideration of the over-etching time, the
metal oxide layer provided below the inorganic compound layer is
subjected to etching for a time period about 0.2 to 1.0 times the
just etching time. Therefore, it is necessary to make the ratio of
the etching rate of the inorganic compound layer composed of Ag or
Al to the etching rate of the metal oxide layer large. [0053] 3. In
the present invention, it is also preferred that the etchant
.lamda. contains 30 to 60 wt % of phosphate ions, 1 to 5 wt % of
nitrate ions, and 30 to 50 wt % of acetate ions.
[0054] If the etchant .lamda. is not a mixed acid having such
negative ion composition, it is difficult to set the etching rate
ratio to 10 or more, thus resulting in a case where the metal oxide
layer provided below the inorganic compound layer is damaged.
Further, if the etchant .lamda. does not have such negative ion
composition described above, there is also a case where the etching
rate is decreased, thereby significantly increasing the time for
etching. Furthermore, if the etchant .lamda. does not have such
negative ion composition described above, there is also a case
where the etching rate is increased so that it becomes impossible
to control the etching rate, thereby causing damage to the metal
oxide layer provided below the inorganic compound layer. [0055] 4.
In the present invention, it is also preferred that the metal oxide
layer contains a lanthanoid group metal oxide.
[0056] If the metal oxide layer composed of at least indium oxide
does not contain a lanthanoid group metal oxide, there is a case
where the etching rate ratio becomes less than 10. Further, if the
metal oxide layer composed of at least indium oxide does not
contain a lanthanoid group metal oxide, it becomes difficult to
etch the metal oxide layer with an acid mainly containing oxalic
acid.
[0057] On the other hand, by adding a lanthanoid group metal oxide
to the metal oxide layer, it is possible to set the etching rate
ratio to 10 or more in most cases. Further, by adding a lanthanoid
group metal oxide to the metal oxide layer, it is possible to etch
the metal oxide layer with an acid mainly containing oxalic acid.
[0058] 5. In the present invention, it is also preferred that the
lanthanoid group metal oxide contains at least one metal oxide
selected from the group consisting of cerium oxide, praseodymium
oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium
oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium
oxide, thulium oxide, ytterbium oxide, and lutetium oxide.
[0059] Preferred examples of a lanthanoid group metal oxide include
cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide,
and terbium oxide, because these metal oxides are atoxic and easily
available. Further, these oxides are preferable from the viewpoint
of price, ease of increase in sintered density due to sintering,
sintering time, and sintering temperature. [0060] 6. In the present
invention, it is also preferred that the ratio of the lanthanoid
group metal oxide contained in the metal oxide layer is 0.1 atomic
% or more but less than 10 atomic % with respect to the total metal
atoms of the metal oxides contained in the metal oxide layer.
[0061] The ratio of the lanthanoid group metal oxide contained in
the metal oxide layer is 0.1 to 20 atomic %, preferably 1 to 8
atomic %, more preferably 2 to 7 atomic %, with respect to the
total metal atoms of the metal oxides contained in the metal oxide
layer.
[0062] If the ratio of the lanthanoid group metal oxide contained
in the metal oxide layer is less than 0.1 atomic % with respect to
the total metal atoms of the metal oxides contained in the metal
oxide layer, there is a case where the effect obtained by adding a
lanthanoid group metal oxide cannot be exhibited, that is, it is
impossible to set the etching rate ratio to 10 or more. On the
other hand, if the ratio of the lanthanoid group metal oxide
contained in the metal oxide layer is 10 atomic % or more with
respect to the total metal atoms of the metal oxides contained in
the metal oxide layer, there is a case where the conductivity of
the metal oxide layer becomes poor and the transparency of the
metal oxide layer is lowered. [0063] 7. In the present invention,
it is also preferred that the inorganic compound layer contains 0.1
to 3 wt % of at least one metal selected from among Au, Pt, and
Nd.
[0064] The present invention can be carried out by using only Ag
for the inorganic compound layer. However, by adding Au, Pt, or Nd
to the inorganic compound layer, it is possible to decrease
resistance, to bring the inorganic compound layer into contact with
a layer provided below the inorganic compound layer more firmly,
and to make the inorganic compound layer more stable toward heat
and moisture. The amount of Au, Pt, or Nd to be added to the
inorganic compound layer is preferably 0.1 to 3 wt %. In the
present invention, it is to be noted that even in a case where a
metal layer provided on the metal oxide layer is composed of Ag or
Al only, the metal layer is referred to as an inorganic compound
layer for the sake of convenience. Further, in the present
invention, a compound obtained by adding Au, Pt, or Nd, to Ag or Al
is also referred to as an inorganic compound for the sake of
convenience.
[0065] If the amount of Au, Pt, or Nd to be added to the inorganic
compound layer is less than 0.1 wt %, it is difficult to obtain the
effects described above, that is, it is difficult to further
decrease resistance, to bring the inorganic compound layer into
contact with the metal oxide layer provided below the inorganic
compound layer more firmly, and to make the inorganic compound
layer more stable toward heat and moisture. On the other hand, if
the amount of Au, Pt, or Nd tobe added to the inorganic compound
layer exceeds 3 wt %, there is a case where resistance is
increased, the contact between the inorganic compound layer and a
layer provided below the inorganic compound layer becomes poor, the
inorganic compound layer becomes unstable toward heat and moisture,
or the resultant product becomes expensive. The amount of Au, Pt,
or Nd to be added to the inorganic compound layer is preferably 0.2
to 2 wt %, more preferably 0.3 to 1.5 wt %.
[0066] The following means 8 to 14 for achieving the first object
have the same operational advantages as the above-described means 1
to 7 except that the means 8 to 14 include the step of forming a
second metal oxide layer on the inorganic compound layer composed
of Al or Ag. [0067] 8. According to the present invention, there is
also provided a method for manufacturing a semi-transparent
semi-reflective electrode substrate in which a first metal oxide
layer composed of at least indium oxide, an inorganic compound
layer composed of at least Al or Ag, and a second metal oxide layer
composed of at least indium oxide or zinc oxide are stacked in
order of mention, the method including the steps of:
[0068] subjecting the second metal oxide layer and the inorganic
compound layer to etching with an etchant .lamda. containing
phosphoric acid, nitric acid, and acetic acid; and
[0069] subjecting the first metal oxide layer to etching with an
etchant .sigma. containing oxalic acid. [0070] 9. In the present
invention, it is preferred that when the etching rate of the first
metal oxide layer with the etchant .lamda. is defined as A and the
etching rate of the inorganic compound layer with the etchant
.lamda. is defined as B, the ratio B/A is 10 or more, and wherein
when the etching rate of the inorganic compound layer with the
etchant .lamda. is defined as C and the etching rate of the second
metal oxide layer with the etchant .lamda. is defined as D, the
ratio C/D is in the range of 0.5 to 2.0. [0071] 10. In the present
invention, it is also preferred that the etchant .lamda. contains
30 to 60 wt % of phosphate ions, 1 to 5 wt % of nitrate ions, and
30 to 50 wt % of acetate ions. [0072] 11. In the present invention,
it is also preferred that the first metal oxide layer contains a
lanthanoid group metal oxide. [0073] 12. In the present invention,
it is also preferred that the lanthanoid group metal oxide contains
at least one metal oxide selected from the group consisting of
cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide,
europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide,
holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, and
lutetium oxide. [0074] 13. In the present invention, it is also
preferred that the ratio of the lanthanoid group metal oxide
contained in the metal oxide layer is 0.1 atomic % or more but less
than 10 atomic % with respect to the total metal atoms of the metal
oxides contained in the metal oxide layer. [0075] 14. In the
present invention, it is also preferred that the inorganic compound
layer contains 0.1 to 3 wt % of at least one metal selected from
among Au, Pt, and Nd.
[0076] Second Invention
[0077] Next, a second invention for mainly achieving the second
object will be described. It is to be noted that the second
invention will be described later in more detail with reference to
a second embodiment.
[0078] In order to achieve the second object, the present inventors
have intensively investigated, and as a result they have found that
by using an inorganic compound layer composed of Al or the like
having a high reflectivity as an electrode layer and using a metal
oxide layer containing a specific element as a charge injection
layer, it is possible to obtain a reflective electrode substrate
having a low specific resistance and a high work function.
[0079] The second invention is divided into the following three
groups (i.e., groups 2-1, 2-2, and 2-3).
[0080] 1. According to the group 2-1 of the second invention, there
is provided a reflective electrode substrate in which an inorganic
compound layer composed of at least Al and a metal oxide layer
composed of at least indium oxide or composed of indium oxide and
one of or both of zinc oxide and tin oxide are stacked in order of
mention on a substrate.
[0081] According to the group 2-2 of the second invention, there is
provided a method for manufacturing such a reflective electrode
substrate described above, including the step of subjecting the
metal oxide layer and the inorganic compound layer to batch etching
with an etchant containing phosphoric acid, nitric acid, and acetic
acid.
[0082] According to the group 2-3 of the second invention, there is
provided an etching composition for an etchant, composed of
phosphoric acid, nitric acid, and acetic acid.
[0083] 2. If the metal oxide layer of the reflective electrode
substrate according to the group 2-1 of the second invention has a
crystalline structure, the surface of the metal oxide layer becomes
rough. In addition, there is a case where a leakage current occurs
due to the irregularities of the surface. If such a reflective
electrode substrate is used for an organic EL device, there is a
case where the luminous efficiency of the organic EL device is
lowered. Therefore, it is necessary for the metal oxide layer to be
amorphous.
[0084] The amount of indium oxide contained in the metal oxide
layer is preferably 60 or more atomic % but less than 100 atomic %
with respect to the total metal atoms of the metal oxides contained
in the metal oxide layer. If the amount of indium oxide contained
in the metal oxide layer is less than 60 atomic % with respect to
the total metal atoms of the metal oxides contained in the metal
oxide layer, the specific resistance of the metal oxide layer is
increased. On the other hand, if the amount of indium oxide
contained in the metal oxide layer is 100 atomic % with respect to
the total metal atoms of the metal oxides contained in the metal
oxide layer, there is a case where the metal oxide layer has a
crystalline structure so that a leakage current occurs. In order to
prevent the crystallization of the metal oxide layer, water or
hydrogen may be added to the metal oxide layer.
[0085] Further, the amount of indium oxide contained in the metal
oxide layer is preferably 96 atomic % or less, more preferably 95
atomic % or less, with respect to the total metal atoms of the
metal oxides contained in the metal oxide layer. By setting the
amount of indium oxide contained in the metal oxide layer to 96
atomic % or less with respect to the total metal atoms of the metal
oxides contained in the metal oxide layer, it is possible to make
the metal oxide layer amorphous without adding water or hydrogen to
the metal oxide layer. Alternatively, zinc oxide may be added to
the metal oxide layer to make the metal oxide layer amorphous. In
this case, the atomic ratio represented by [In]/([In]+[Zn]) is in
the range of 0.7 to 0.95, preferably in the range of 0.85 to 0.95,
more preferably in the range of 0.8 to 0.9. Here, [In] and [Zn]
represent the number of indium atoms and the number of zinc atoms
in the metal oxide layer, respectively. It is to be noted that the
word "number of atoms" means the number of atoms per unit volume in
the composition of the metal oxide layer.
[0086] The thickness of the metal oxide layer is in the range of 2
to 300 nm, preferably in the range of 30 to 200 nm, more preferably
in the range of 10 to 120 nm. If the thickness of the metal oxide
layer is less than 2 nm, it is impossible to sufficiently protect
the inorganic compound layer. On the other hand, if the thickness
of the metal oxide layer exceeds 300 nm, the reflectivity of the
reflective electrode substrate is lowered.
[0087] The thickness of the inorganic compound layer is in the
range of 10 to 300 nm, preferably in the range of 30 to 250 nm,
more preferably in the range of 50 to 200 nm. If the thickness of
the inorganic compound layer is less than 10 nm, there is a case
where light emitted from a light-emitting layer cannot be
sufficiently reflected. In addition, there is also a case where the
resistance of the reflective electrode becomes too high. On the
other hand, if the thickness of the inorganic compound layer
exceeds 300 nm, there is a case where a step is produced in the
inorganic compound layer due to batch etching of the metal oxide
layer and the inorganic compound layer with an etchant. The surface
of the inorganic compound layer may be a diffuse reflector.
[0088] A material for forming a substrate on which the inorganic
compound layer etc. are to be provided is not particularly limited.
Examples of a material for forming a substrate include glass,
plastics, and silicon.
[0089] The inorganic compound layer contains Al as a main
ingredient, and preferably contains 0.1 to 3 wt % of at least one
metal selected from among Au, Pt, and Nd in addition to Al.
[0090] The amount of at least one metal selected from among Au, Pt,
and Nd to be added to the inorganic compound layer is 0.1 to 3 wt
%, preferably 0.1 to 2 wt %, more preferably 0.5 to 2 wt %. If the
amount of at least one metal selected from among Au, Pt, and Nd to
be added to the inorganic compound layer is less than 0.1 wt %, the
effect obtained by adding such a metal is not sufficiently
exhibited. On the other hand, if the amount of at least one metal
selected from among Au, Pt, and Nd to be added to the inorganic
compound layer exceeds 3 wt %, the conductivity of the inorganic
compound layer is lowered.
[0091] A metal other than the above-mentioned metals such as Au may
be added as a third ingredient to the inorganic compound layer as
long as the third ingredient does not affect the stability and
resistance of the inorganic compound layer. The word "third
ingredient" means a metal ingredient other than the main ingredient
Al and the above-mentioned metals such as Au.
[0092] The work function of the metal oxide layer is 5.6 eV or
more. In a case where the reflective electrode substrate having a
metal oxide layer with a work function of 5.6 eV or more is used
for an organic EL device, it is possible to increase the luminous
efficiency of the organic EL device. For this reason, the work
function of the metal oxide layer is preferably 5.6 eV or more,
more preferably 5.8 eV or more.
[0093] By adding a lanthanoid group metal oxide to the metal oxide
layer, it is easy for the metal oxide layer to have a work function
of 5.6 eV or more.
[0094] The lanthanoid group metal oxide contains at least one metal
oxide selected from the group consisting of cerium oxide,
praseodymium oxide, neodymium oxide, samarium oxide, europium
oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium
oxide, erbium oxide, thulium oxide, ytterbium oxide, and lutetium
oxide.
[0095] The ratio of the lanthanoid group metal oxide contained in
the metal oxide layer is 0.1 to 10 atomic % with respect to the
total metal atoms of the metal oxides contained in the metal oxide
layer.
[0096] The ratio of the lanthanoid group metal oxide contained in
the metal oxide layer is 0.1 atomic % or more but less than 10
atomic %, preferably l atomic % or more but less than 10 atomic %,
more preferably 2 atomic % or more but less than 5 atomic %, with
respect to the total metal atoms of the metal oxides contained in
the metal oxide layer. If the ratio of the lanthanoid group metal
oxide contained in the metal oxide layer is less than 0.1 atomic %
with respect to the total metal atoms of the metal oxides contained
in the metal oxide layer, there is a case where the metal oxide
layer cannot have a work function of 5.6 eV or more. On the other
hand, if the ratio of the lanthanoid group metal oxide contained in
the metal oxide layer is 10 atomic % or more with respect to the
total metal atoms of the metal oxides contained in the metal oxide
layer, there is a case where the specific resistance of the metal
oxide layer becomes too high so that the conductivity thereof is
lowered.
[0097] 3. The reflective electrode substrate according to the group
2-1 of the second invention can be manufactured by a method
according the group 2-2 of the second invention.
[0098] The metal oxide layer is preferably formed in an atmosphere
having an oxygen partial pressure of 0 to 5%. If the oxygen partial
pressure exceeds 5%, there is a case where the specific resistance
of the metal oxide layer becomes too high. The oxygen partial
pressure is more preferably 0 to 2%, particularly preferably 0 to
1%.
[0099] The manufacturing method of a reflective electrode substrate
according to the group 2-2 of the second invention includes the
step of subjecting the metal oxide layer and the inorganic compound
layer to batch etching with an etchant containing phosphoric acid,
nitric acid, and acetic acid.
[0100] When the etching rate of the inorganic compound layer with
the etchant described above is defined as A, and the etching rate
of the metal oxide layer with the etchant described above is
defined as B, the ratio B/A is set to 0.5 to 2.0.
[0101] The ratio of the etching rate B to the etching rate A, that
is, the ratio B/A is in the range of 0.5 to 2.0, preferably in the
range of 0.6 to 1.5, more preferably in the range of 0.6 to 1.2. If
the etching rate ratio B/A is less than 0.5, the etching rate B
becomes too fast relative to the etching rate A so that there is a
case where the inorganic compound layer is more widely etched than
the metal oxide layer, and as a result a step is produced at the
boundary between the metal oxide layer and the inorganic compound
layer. On the other hand, if the etching rate ratio B/A exceeds
2.0, the etching rate B is too slow relative to the etching rate A
so that there is a case where the metal oxide layer is more widely
etched than the inorganic compound layer, and as a result, a step
is produced at the boundary between the metal oxide layer and the
inorganic compound layer.
[0102] The etchant is composed of 30 to 60 wt % of phosphoric acid,
1 to 5 wt % of nitric acid, and 30 to 50 wt % of acetic acid. If
the concentration of phosphoric acid in the etchant is less than 30
wt %, or the concentration of nitric acid in the etchant is less
than 1 wt %, or the concentration of acetic acid in the etchant is
less than 30 wt %, there is a case where the life span of the
etchant is shortened. In addition, there is also a case where the
inorganic compound layer is not sufficiently etched so that
residues are left, or it becomes impossible to subject the metal
oxide layer and the inorganic compound layer to batch etching.
[0103] On the other hand, if the concentration of phosphoric acid
in the etchant exceeds 65 wt %, or the concentration of nitric acid
in the etchant exceeds 5 wt %, or the concentration of acetic acid
in the etchant exceeds 50 wt %, the etching rate A and the etching
rate B become too fast so that there is a case where the etching
rates cannot be controlled and therefore the etching rate ratio B/A
cannot be set to a value within the above range (i.e., 0.5 to 2.0).
In addition, there is also a case where the metal oxide layer is
deteriorated.
[0104] The etchant is more preferably composed of 30 to 50 wt % of
phosphoric acid, 1 to 5 wt % of nitric acid, and 30 to 50 wt % of
acetic acid.
[0105] By adding a lanthanoid group metal oxide to the metal oxide
layer, it becomes easy to control the etching rate of the metal
oxide layer, thereby enabling the etching rate ratio B/A to be set
to 0.5 to 2.0 easily.
[0106] The metal oxide layer is preferably amorphous. When the
metal oxide layer is amorphous, substantially no residue is left on
the end face obtained by etching (that is, on the etched surface)
In addition, the obtained reflective electrode has a tapered shape,
and therefore a short circuit hardly occurs between the reflective
electrode and an electrode to be provided opposite to the
reflective electrode.
[0107] 4. The group 2-3 according to the second invention is
directed to an etchant to be used for etching in the manufacturing
method of a reflective electrode substrate according to the group
2-2 of the second invention, including an etching composition
containing 30 to 60 wt % of phosphoric acid, 1 to 5 wt % of nitric
acid, and 30 to 50 wt % of acetic acid. Here, the word "etching
composition" means a composition contained in an etchant.
[0108] Third Invention
[0109] Next, a third invention for mainly achieving the third
object will be described. It is to be noted that the third
invention will be described later in more detail with reference to
a third embodiment.
[0110] The third invention is divided into the following two groups
(i.e., groups 3-1 and 3-2).
[0111] In order to achieve the third object, the present inventors
have intensively investigated, and as a result they have found that
by using an electrode layer obtained by stacking an inorganic
compound layer composed of Ag or the like having a high
reflectivity and a metal oxide layer containing a specific element,
it is possible to obtain a reflective electrode substrate having a
low specific resistance and a high work function.
[0112] 1. Group 3-1 (Reflective Electrode Substrate)
[0113] According to the group 3-1 of the third invention, there is
provided a reflective electrode substrate in which an inorganic
compound layer composed of at least Ag and a metal oxide layer
composed of at least indium oxide and a lanthanoid group metal
oxide are stacked on a substrate in order of mention. According to
the group 3-2 of the third invention, there is provided a method
for manufacturing the reflective electrode substrate according to
the group 3-1, including the steps of subjecting the metal oxide
layer to etching with an etchant containing oxalic acid, and
subjecting the inorganic compound layer to etching with an etchant
containing phosphoric acid, nitric acid, and acetic acid.
[0114] If the metal oxide layer of the reflective electrode
substrate according to the group 3-1 of the third invention has a
crystalline structure, the surface of the metal oxide layer becomes
rough. In addition, there is also a case where a leakage current
occurs due to the irregularities of the surface. If such a
reflective electrode substrate is used for an organic EL device,
there is a case where the luminous efficiency of the organic EL
device is lowered. Therefore, it is necessary for the metal oxide
layer to be amorphous.
[0115] The amount of indium atoms contained in the metal oxide
layer is preferably 60 atomic % or more with respect to the total
metal atoms contained in the metal oxide layer. If the amount of
indium atoms contained in the metal oxide layer is less than 60
atomic % with respect to the total metal atoms contained in the
metal oxide layer, the specific resistance of the metal oxide layer
is increased. In order to prevent the occurrence of a leakage
current due to the crystallization of the metal oxide layer, water
or hydrogen may be added to the metal oxide layer when the metal
oxide layer is formed. Further, the amount of. indium atoms
contained in the metal oxide layer is preferably 96 atomic % or
less, more preferably 95 atomic % or less, with respect to the
total metal atoms contained in the metal oxide layer. By setting
the amount of indium atoms contained in the metal oxide layer to 96
atomic % or less with respect to the total metal atoms contained in
the metal oxide layer, it is possible to make the metal oxide layer
amorphous without adding water or hydrogen to the metal oxide layer
when the metal oxide layer is formed, thereby preventing the
occurrence of a leakage current. Alternatively, zinc oxide may be
added to the metal oxide layer to make the metal oxide layer
amorphous. In this case, the atomic ratio represented by
[In]/([In]+[Zn]) is in the range of 0.7 to 0.95, preferably in the
range of 0.85 to 0.95, more preferably in the range of 0.8 to 0.9.
Here, [In] and [Zn] represent the number of indium atoms and the
number of zinc atoms in the metal oxide layer, respectively.
Alternatively, tin oxide may be added to the metal oxide layer
instead of zinc oxide or tin oxide may be added to the metal oxide
layer together with zinc oxide. In this case, the atomic ratio
represented by [In]/([In]+[Sn]) is in the range of 0.7 to 0.97,
preferably in the range of 0.85 to 0.95, more preferably in the
range of 0.85 to 0.95. Here, [Sn] represents the number of tin
atoms in the metal oxide layer. It is to be noted that the word
"number of atoms" means the number of atoms per unit volume in the
composition of the metal oxide layer.
[0116] The work function of the metal oxide layer is preferably
5.25 eV or more, more preferably 5.60 eV or more, even more
preferably 5.80 eV or more.
[0117] The lanthanoid group metal oxide contains at least one metal
oxide selected from the group consisting of cerium oxide,
praseodymium oxide, neodymium oxide, samarium oxide, europium
oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium
oxide, erbium oxide, thulium oxide, ytterbium oxide, and lutetium
oxide.
[0118] The ratio of the lanthanoid group metal atoms contained in
the metal oxide layer is 0.1 to 20 atomic % with respect to the
total metal atoms of the metal oxides contained in the metal oxide
layer.
[0119] The ratio of the lanthanoid group metal atoms contained in
the metal oxide layer is preferably 1 or more atomic % but less
than 10 atomic %, more preferably 2 or more atomic % but less than
5 atomic %, with respect to the total metal atoms of the metal
oxides contained in the metal oxide layer. If the ratio of the
lanthanoid group metal atoms contained in the metal oxide layer is
less than 0.1 atomic % with respect to the total metal atoms of the
metal oxides contained in the metal oxide layer, there is a case
where the metal oxide layer cannot have a work function of 5.25 eV
or more. On the other hand, if the ratio of the lanthanoid group
metal atoms contained in the metal oxide layer is 20 atomic % or
more with respect to the total metal atoms of the metal oxides
contained in the metal oxide layer, there is a case where the
specific resistance of the metal oxide layer becomes too high so
that the conductivity of the metal oxide layer is lowered.
[0120] The thickness of the metal oxide layer is in the range of 2
to 300 nm, preferably in the range of 30 to 200 nm, more preferably
in the range of 10 to 120 nm. If the thickness of the metal oxide
layer is less than 2 nm, it is impossible to sufficiently protect
the inorganic compound layer. On the other hand, if the thickness
of the metal oxide layer exceeds 300 nm, the reflectivity of the
reflective electrode substrate is lowered.
[0121] The thickness of the inorganic compound layer is in the
range of 10 to 300 nm, preferably in the range of 30 to 250 nm,
more preferably in the range of 50 to 200 nm. If the thickness of
the inorganic compound layer is less than 10 nm, there is a case
where light emitted from a light-emitting layer is not sufficiently
reflected. In addition, there is also a case where the resistance
of the reflective electrode becomes too high. On the other hand, if
the thickness of the inorganic compound layer exceeds 300 nm, there
is a case where a step is produced in the inorganic compound layer
due to etching of the inorganic compound layer with an etchant. The
surface of the inorganic compound layer may be a diffusion
reflector.
[0122] A material for forming a substrate on which the inorganic
compound layer etc. are to be provided is not particularly limited.
Examples of a material for forming a substrate include glass,
plastics, and silicon.
[0123] The inorganic compound layer preferably contains 0.1 to 3 wt
% of at least one metal selected from among Au, Cu, Pd, Zr, Ni, Co,
and Nd, in addition to Ag that is a main ingredient.
[0124] The amount of at least one metal selected from among Au, Cu,
Pd, Zr, Ni, Co, and Nd to be added to the inorganic compound layer
is 0.1 to 3 wt %, preferably 0.1 to 2 wt %, more preferably 0.5 to
2 wt %. If the amount of at least one metal selected from among Au,
Cu, Pd, Zr, Ni, Co, and Nd to be added to the inorganic compound
layer is less than 0.1 wt %, the effect obtained by adding such a
metal is not sufficiently exhibited. On the other hand, if the
amount of at least one metal selected from among Au, Cu, Pd, Zr,
Ni, Co, and Nd to be added to the inorganic compound layer exceeds
3 wt %, the conductivity of the inorganic compound layer is
lowered.
[0125] A metal other than the above-mentioned metals such as Au may
be added as a third ingredient to the inorganic compound layer as
long as the third ingredient does not affect the stability and
resistance of the inorganic compound layer.
[0126] 2. Group 3-2 (Manufacturing Method)
[0127] The reflective electrode substrate according to the group
3-1 of the third invention can be formed by the following
manufacturing method according to the group 3-2 of the third
invention.
[0128] The metal oxide layer is preferably formed by sputtering in
an atmosphere having an oxygen partial pressure of 0 to 5%. If the
oxygen partial pressure exceeds 5%, there is a case where the
specific resistance of the metal oxide layer becomes too high. The
oxygen partial pressure is more preferably 0 to 2%, particularly
preferably 0 to 1%.
[0129] The manufacturing method according to the group 3-2 of the
third invention has the steps of subjecting the metal oxide layer
to etching with an etchant containing oxalic acid, and subjecting
the inorganic compound layer to etching with an etchant containing
phosphoric acid, nitric acid, and acetic acid.
[0130] The etchant to be used for etching the metal oxide layer
preferably contains 1 to 10 wt % of oxalic acid. If the
concentration of oxalic acid is less than 1 wt %, there is a case
where the etching rate of the metal oxide layer becomes slow. On
the other hand, if the concentration of oxalic acid exceeds 10 wt
%, there is a case where oxalic acid is crystallized. The
concentration of oxalic acid in the etchant is particularly
preferably 2 to 5 wt %.
[0131] The etchant to be used for etching the inorganic compound
layer is composed of 30 to 60 wt % of phosphoric acid, 1 to 5 wt %
of nitric acid, and 30 to 50 wt % of acetic acid. If the
concentration of phosphoric acid in the etchant to be used for
etching the inorganic compound layer is less than 30 wt %, or the
concentration of nitric acid in the etchant is less than 1 wt %, or
the concentration of acetic acid in the etchant is less than 30 wt
%, there is a case where the life span of the etchant is shortened.
In addition, there is also a case where the inorganic compound
layer is not sufficiently etched so that residues are left, or it
is impossible to etch the inorganic compound layer.
[0132] The etchant to be used for etching the inorganic compound
layer is more preferably composed of 30 to 50 wt % of phosphoric
acid, 1 to 5 wt % of nitric acid, and 30 to 50 wt % of acetic
acid.
[0133] The metal oxide layer of the reflective electrode substrate
of the present invention is amorphous. Therefore, substantially no
residue is left on the end face obtained by etching (that is, on
the etched surface). In addition, the obtained reflective electrode
has a tapered shape, and therefore a short circuit hardly occurs
between the reflective electrode and an electrode to be provided
opposite to the reflective electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0134] FIGS. 1(1) to 1(5) are cross-sectional views which show the
manufacturing steps of a semi-transparent semi-reflective electrode
substrate according to an example of a first embodiment of the
present invention;
[0135] FIGS. 2(1) to 2(6) are cross-sectional views which show the
manufacturing steps of a semi-transparent semi-reflective electrode
substrate according to another example of the first embodiment of
the present invention;
[0136] FIG. 3 is a cross-sectional view of the semi-transparent
semi-reflective electrode substrate according to an example of the
first embodiment of the present invention;
[0137] FIG. 4 is a cross-sectional view of the semi-transparent
semi-reflective electrode substrate according to another example of
the first embodiment of the present invention;
[0138] FIG. 5 is a plan view of the semi-transparent
semi-reflective electrode substrate according to an example of the
first embodiment of the present invention;
[0139] FIG. 6 is a plan view of the semi-transparent
semi-reflective electrode substrate according to another example of
the first embodiment of the present invention;
[0140] FIG. 7 is a cross-sectional view of a conventional
semi-transparent semi-reflective electrode substrate;
[0141] FIGS. 8(1) to (4) are cross-sectional views which show the
manufacturing steps of a reflective electrode substrate according
to an example of a second embodiment of the present invention;
[0142] FIG. 9 is a vertical cross-sectional view of the reflective
electrode substrate according to an example of the second
embodiment of the present invention;
[0143] FIGS. 10(1) to (4) are cross-sectional views which show a
reflective electrode substrate and the manufacturing method thereof
according to an example of a third embodiment of the present
invention; and
[0144] FIG. 11 is a vertical cross-sectional view of the reflective
electrode substrate according to an example of the third embodiment
of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0145] Hereinbelow, preferred embodiments according to the present
invention will be described in detail with reference to the
accompanying drawings.
[0146] First Embodiment
[0147] Hereinbelow, a preferred first embodiment according to the
present invention will be described with reference to the
accompanying drawings. The first embodiment is an embodiment
related to the first invention, and will be described with
reference to 11 examples (i.e., Examples 1-1 to 1-11) and 2
comparative examples (i.e., Comparative Examples 1-1 and 1-2).
EXAMPLE 1-1
[0148] First, a blue plate glass substrate 10 coated with SiO.sub.2
was prepared (see FIG. 1(1)). On such a blue plate glass substrate
10, a metal oxide layer 12 was formed using a first target composed
of indium oxide-cerium oxide (Ce/(In+Ce)=4.5 atomic %) with a DC
magnetron sputtering system (manufactured by Shinko Seiki Co.,
Ltd.) (see FIG. 1(2)).
[0149] In this regard, it is to be noted that the temperature of
the blue plate glass substrate 10 at the time when the metal oxide
layer 12 was formed was 200.degree. C., the thickness of the metal
oxide layer 12 was 75 nm, and the specific resistance of the metal
oxide layer 12 was 380 .mu..OMEGA.cm.
[0150] Next, on the metal oxide layer 12, an inorganic compound
layer 14 was formed using an Ag target composed of Ag--Pd--Cu
(98.5:0.5:1.0 wt %) (see FIG. 1(3)). The thickness of the inorganic
compound layer 14 was 100 nm. It is to be noted that the metal
oxide layer 12 and the inorganic compound layer 14 containing Ag as
a main ingredient are collectively called an electrode layer. In
FIGS. 1 to 4, a layer formed on the metal oxide layer 12 or 12a is
referred to as an inorganic compound layer 14 composed of Ag or Al,
for the sake of convenience. However, such an inorganic compound
layer 14 may be composed of Ag or Al only or a compound containing
Ag or Al as a main ingredient. In this regard, it is to be noted
that in the present invention, a compound obtained by adding Au,
Pt, or Nd to Ag or Al is referred to as an inorganic compound for
the sake of convenience.
[0151] Next, the inorganic compound layer 14 was subjected to
etching. After the completion of etching, residual portions were
provided as a plurality of lines of the inorganic compound layer 14
(see FIG. 1(4)).
[0152] A mask pattern used for etching was designed such that the
width of each of the lines of the inorganic compound layer 14
became 40 .mu.m and the space between the adjacent lines of the
inorganic compound layer 14 became 70 .mu.m.
[0153] Etching of the inorganic compound layer 14 was carried out
in the following manner using the mask pattern described above.
First, a resist was applied onto the inorganic compound layer 14. A
glass plate having the mask pattern was placed on the resist, and
then the resist was exposed to light, developed, and
post-baked.
[0154] Next, the inorganic compound layer 14 was subjected to
etching using an aqueous solution containing 40 wt % of phosphate
ions, 2.5 wt % of nitrate ions, and 40 wt % of acetate ions so that
the over-etching time became 100% of the just etching time (see
FIG. 1(4)). It is to be noted that the aqueous solution is one
example of an etchant .lamda. claimed in the present invention.
[0155] Next, the blue plate glass substrate 10 which had been
subjected to etching was washed with water, and was then dried.
[0156] Next, the metal oxide layer 12 was subjected to etching.
After the completion of etching, residual portions were provided as
a plurality of lines of the metal oxide layer 12 (see FIG.
1(5)).
[0157] A mask pattern used for etching of the metal oxide layer 12
was designed such that the width of each of the lines of the metal
oxide layer 12 became 90 .mu.m and the space between the adjacent
lines of the metal oxide layer 12 became 20 .mu.m.
[0158] Etching of the metal oxide layer 12 was carried out in the
following manner using the mask pattern described above. First, a
resist was applied onto the electrode layer. A glass plate having
the mask pattern was placed on the resist, and then the resist was
exposed to light, developed, and post-baked (see FIG. 1(5)). In
this regard, it is to be noted that exposure of the resist was
carried out in such a manner that one of the side edges of each
line of the inorganic compound layer 14 and one of the side edges
of each line of the metal oxide layer 12 were overlapped one
another as shown in FIG. 3.
[0159] Next, the metal oxide layer 12 was subjected to etching
using a 4 wt % aqueous oxalic acid solution. It is to be noted that
the aqueous solution is one example of an etchant .sigma. claimed
in the present invention. After the resist was removed, the
resistance of one of the electrodes having a length of 5 cm was
measured and was found to be 0.65 k.OMEGA..
[0160] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0161] It is to be noted that in a case where the aqueous solution
containing 40 wt % of phosphate ions, 2.5 wt % of nitrate ions, and
40 wt % of acetate ions at a temperature of 30.degree. C. was used
as an etchant, the ratio of the etching rate of the inorganic
compound layer 14 to that of the metal oxide layer 12 was 40.
EXAMPLE 1-2
[0162] A first metal oxide layer 12a and an inorganic compound
layer 14 were formed in the same manner as in Example 1-1 except
that the first target was changed to a second target composed of
indium oxide-tin oxide-cerium oxide (In/(In+Sn)=90 atomic %,
Ce/(In+Sn+Ce)=4.9 atomic %) and that Ag--Pd--Cu (98.5:0.5:1.0 wt %)
was changed to Ag--Au--Ni (98.5:0.5:1.0 wt %) (see FIGS. 2(1) to
2(3)). It is to be noted that the first metal oxide layer 12a of
Example 1-2, that is, the first metal oxide layer 12a shown in FIG.
2(2) corresponds to the metal oxide layer 12 shown in FIG.
1(2).
[0163] Next, a second metal oxide layer 16 was formed as a
protection film by the use of a third target composed of indium
oxide and zinc oxide (In/(In+Zn)=75 atomic %) at room temperature
(see FIG. 2(4)). The thickness of the second metal oxide layer 16
was 20 nmm.
[0164] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate (see FIGS. 2(5) and 2(6)). The specific
resistance of the first metal oxide layer 12a was 320
.mu..OMEGA.cm, and the electrode resistance was 0.61 k.OMEGA..
[0165] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12a. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0166] It is to be noted that in a case where an aqueous solution
containing 30 wt % of phosphate ions, 1.5 wt % of nitrate ions, and
40 wt % of acetate ions at a temperature of 30.degree. C. was used
as an etchant, the ratio of the etching rate of the inorganic
compound layer 14 to that of the first metal oxide layer 12a was
45.
[0167] Further, it is to be noted that in a case where an aqueous
solution containing 30 wt % of phosphate ions, 1.5 wt % of nitrate
ions, and 40 wt % of acetate ions at a temperature of 30.degree. C.
was used as an etchant, the ratio of the etching rate of the
inorganic compound layer 14 to that of the second metal oxide layer
16 was 1.5.
EXAMPLE 1-3
[0168] A metal oxide layer 12 and an inorganic compound layer 14
were formed in the same manner as in Example 1-1 except that the
first target was changed to a fourth target composed of indium
oxide-tin oxide-praseodymium oxide (In/(In+Sn)=90 atomic %,
Pr/(In+Sn+Pr)=4.6 atomic %) (see FIGS. 1(1) to 1(3)).
[0169] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate (see FIGS. 1(4) and 1(5)). The specific
resistance of the metal oxide layer 12 was 450 .mu..OMEGA.cm.
[0170] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0171] It is to be noted that in a case where an aqueous solution
containing 30 wt % of phosphate ions, 1.5 wt % of nitrate ions, and
40 wt % of acetate ions at a temperature of 30.degree. C. was used
as an etchant, the ratio of the etching rate of the inorganic
compound layer 14 to that of the metal oxide layer 12 was 38.
EXAMPLE 1-4
[0172] A metal oxide layer 12 and an inorganic compound layer 14
were formed in the same manner as in Example 1-1 except that the
first target was changed to a fifth target composed of indium
oxide-tin oxide-neodymium oxide (In/(In+Sn)=90 atomic %,
Nd/(In+Sn+Nd)=3.8 atomic %) and that Ag--Pd--Cu (98.5:0.5:1.0 wt %)
was changed to Ag--Pt--Co (98.5:0.5:1.0 wt %) (see FIGS. 1(1) to
1(3)).
[0173] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate (see FIGS. 1(4) and 1(5)). The specific
resistance of the metal oxide layer 12 was 420 .mu..OMEGA.cm, and
the electrode resistance was 0.67 k.OMEGA..
[0174] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0175] It is to be noted that in a case where an aqueous solution
containing 30 wt % of phosphate ions, 1.5 wt % of nitrate ions, and
40 wt % of acetate ions at a temperature of 30.degree. C. was used
as an etchant, the ratio of the etching rate of the inorganic
compound layer 14 to that of the metal oxide layer 12 was 48.
EXAMPLE 1-5
[0176] A metal oxide layer 12 and an inorganic compound layer 14
were formed in the same manner as in Example 1-1 except that the
first target was changed to a sixth target composed of indium
oxide-tin oxide-samarium oxide (In/(In+Sn)=90 atomic %,
Sm/(In+Sn+Sm)=3.2 atomic %) and that Ag--Pd--Cu (98.5:0.5:1.0 wt %)
was changed to Ag--Co--Ni (98.0:1.0:1.0 wt %) (see FIGS. 1(1) to
1(3)).
[0177] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate (see FIGS. 1(4) and 1(5)). The specific
resistance of the metal oxide layer 12 was 720 .mu..OMEGA.cm, and
the electrode resistance was 0.72 k.OMEGA..
[0178] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0179] It is to be noted that in a case where an aqueous solution
containing 30 wt % of phosphate ions, 1.5 wt % of nitrate ions, and
40 wt % of acetate ions at a temperature of 30.degree. C. was used
as an etchant, the ratio of the etching rate of the inorganic
compound layer 14 to that of the metal oxide layer 12 was 40.
EXAMPLE 1-6
[0180] A metal oxide layer 12 and an inorganic compound layer 14
were formed in the same manner as in Example 1-1 except that the
first target was changed to a seventh target composed of indium
oxide-tin oxide-terbium oxide (In/(In+Sn)=90 atomic %,
Tb/(In+Sn+Tb)=4.7 atomic %) (see FIGS. 1(1) to 1(3)).
[0181] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate (see FIGS. 1(4) and 1(5)). The specific
resistance of the metal oxide layer 12 was 1,450 .mu..OMEGA.cm.
[0182] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0183] It is to be noted that in a case where an aqueous solution
containing 30 wt % of phosphate ions, 1.5 wt % of nitrate ions, and
40 wt % of acetate ions at a temperature of 30.degree. C. was used
as an etchant, the ratio of the etching rate of the inorganic
compound layer 14 to that of the metal oxide layer 12 was 46.
EXAMPLE 1-7
[0184] First, a blue plate glass substrate 10 coated with SiO.sub.2
was prepared (see FIG. 1(1)). On such a blue plate glass substrate
10, a metal oxide layer 12 was formed using the first target
composed of indium oxide-cerium oxide (Ce/(In+Ce)=4.5 atomic %)
(see FIG. 1(2)). In this regard, it is to be noted that the
temperature of the blue plate glass substrate 10 at the time when
the metal oxide layer 12 was formed was 200.degree. C., the
thickness of the metal oxide layer 12 was 75 nm, and the specific
resistance of the metal oxide layer 12 was 380 .mu..OMEGA.cm. Next,
on the metal oxide layer 12, an inorganic compound layer 14 was
formed using an Al target composed of Al--Nd (99:1 wt %) (see FIG.
1(3)). The thickness of the inorganic compound layer 14 was 100 nm.
It is to be noted that the metal oxide layer 12 and the inorganic
compound layer 14 containing Al as a main ingredient are
collectively called an electrode layer.
[0185] It is to be noted that semi-transparent semi-reflective
electrode substrates according to Examples 1-7 to 1-11 were
manufactured in substantially the same manner as in Example 1-1
except that the main ingredient of the metal oxide layer 12 was
changed from Ag to Al.
[0186] Next, the inorganic compound layer 14 was subjected to
etching. After the completion of etching, residual portions were
provided as a plurality of lines of the inorganic compound layer 14
(see FIG. 1(4)).
[0187] A mask pattern used for etching was designed such that the
width of each of the lines of the inorganic compound layer 14
became 40 .mu.m and the space between the adjacent lines of the
inorganic compound layer 14 became 70 .mu.m.
[0188] Etching of the inorganic compound layer 14 was carried out
in the following manner using the mask pattern described above.
First, a resist was applied onto the inorganic compound layer 14. A
glass plate having the mask pattern was placed on the resist, and
then the resist was exposed to light, developed, and
post-baked.
[0189] Next, the inorganic compound layer 14 was subjected to
etching using an aqueous solution containing 50 wt % of phosphate
ions, 2.0 wt % of nitrate ions, and 40 wt % of acetate ions so that
the over etching time became 100% of the just etching time (see
FIG. 1(4)). It is to be noted that the aqueous solution is one
example of an etchant .lamda. claimed in the present invention.
[0190] Next, the blue plate glass substrate 10 which had been
subjected to etching was washed with water, and was then dried.
[0191] Next, the metal oxide layer 12 was subjected to etching.
After the completion of etching, residual portions were provided as
a plurality of lines of the metal oxide layer 12 (see FIG.
1(5)).
[0192] A mask pattern used for etching the metal oxide layer 12 was
designed such that the width of each of the lines of the metal
oxide layer 12 became 90 .mu.m and the space between the adjacent
lines of the metal oxide layer 12 became 20 .mu.m.
[0193] Etching of the metal oxide layer 12 was carried out in the
following manner using the mask pattern described above. First, a
resist was applied onto the electrode layer. A glass plate having
the mask pattern was placed on the resist, and then the resist was
exposed to light, developed, and post-baked (see FIG. 1(5)). In
this regard, it is to be noted that exposure of the resist was
carried out in such a manner that one of the side edges of each
line of the inorganic compound layer 14 and one of the side edges
of each line of the metal oxide layer 12 were overlapped one
another.
[0194] Next, the metal oxide layer 12 was subjected to etching
using a 4 wt % aqueous oxalic acid solution. It is to be noted that
the aqueous solution is one example of an etchant .sigma. claimed
in the present invention. After the resist was removed, the
resistance of one of the electrodes having a length of 5 cm was
measured and was found to be 0.65 k.OMEGA..
[0195] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0196] It is to be noted that in a case where an aqueous solution
containing 50 wt % of phosphate ions, 2.0 wt % of nitrate ions, and
40 wt % of acetate ions at a temperature of 30.degree. C. was used
as an etchant, the ratio of the etching rate of the inorganic
compound layer 14 to that of the metal oxide layer 12 was 16.
EXAMPLE 1-8
[0197] A first metal oxide layer 12a and an inorganic compound
layer 14 were formed in the same manner as in Example 1-7 except
that the first target was changed to the second target composed of
indium oxide-tin oxide-cerium oxide (In/(In+Sn)=90 atomic %,
Ce/(In+Sn+Ce)=4.9 atomic %) and that Al--Nd (99:1 wt %) was changed
to Al--Pt (99:1 wt %) (see FIGS. 2(1) to 2(3)). It is to be noted
that the first metal oxide layer 12a of Example 1-8, that is, the
first metal oxide layer 12a shown in FIG. 2(2) corresponds to the
metal oxide layer 12 shown in FIG. 1(2).
[0198] Next, a second metal oxide layer 16 was formed as a
protection film by the use of a target 3 composed of indium oxide
and zinc oxide (In/(In+Zn)=85 atomic %) at room temperature (see
FIG. 2(4)). The thickness of the second metal oxide layer 16 was 20
nmm.
[0199] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate (see FIGS. 2(5) and 2(6)). The specific
resistance of the indium oxide-tin oxide-cerium oxide layer was 320
.mu..OMEGA.cm, and the electrode resistance was 1.57 k.OMEGA..
[0200] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12a. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0201] It is to be noted that the ratio of the etching rate of the
inorganic compound layer 14 to that of the first metal oxide layer
12a was 18, and that the ratio of the etching rate of the inorganic
compound layer 14 to that of the second metal oxide layer 16 was
1.1.
EXAMPLE 1-9
[0202] A metal oxide layer 12 and an inorganic compound layer 14
were formed in the same manner as in Example 1-7 except that the
first target was changed to the fourth target composed of indium
oxide-tin oxide-praseodymium oxide (In/(In+Sn)=90 atomic %,
Pr/(In+Sn+Pr)=4.6atomic %) (see FIGS. 1(1) to 1(3)).
[0203] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate (see FIGS. 1(4) and 1(5)). The specific
resistance of the metal oxide layer 12 was 450 .mu..OMEGA.cm, and
the electrode resistance was 1.66 k.OMEGA..
[0204] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0205] It is to be noted that the ratio of the etching rate of the
inorganic compound layer 14 to that of the metal oxide layer 12 was
15.
EXAMPLE 1-10
[0206] A metal oxide layer 12 and an inorganic compound layer 14
were formed in the same manner as in Example 1-7 except that the
first target was changed to the fifth target composed of indium
oxide-tin oxide-neodymium oxide (In/(In+Sn)=90 atomic %,
Nd/(In+Sn+Nd)=3.8 atomic %) and that Al--Nd (99:1 wt %) was changed
to Al--Au (99:1 wt %) (see FIGS. 1(1) to 1(3)).
[0207] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate (see FIGS. 1(4) and 1(5)). The specific
resistance of the indium oxide-tin oxide-neodymium oxide layer was
420 .mu..OMEGA.cm, and the electrode resistance was 1.39
k.OMEGA..
[0208] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0209] It is to be noted that the ratio of the etching rate of the
inorganic compound layer 14 to that of the metal oxide layer 12 was
18.
EXAMPLE 1-11
[0210] A metal oxide layer 12 and an inorganic compound layer 14
were formed in the same manner as in Example 1-7 except that the
first target was changed to the sixth target composed of indium
oxide-tin oxide-samarium oxide (In/(In+Sn)=90 atomic %,
Sm/(In+Sn+Sm)=3.2 atomic %) and that Al--Nd (99:1 wt %) was changed
to Al (100 wt %) (see FIGS. 1(1) to 1(3)).
[0211] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate (see FIGS. 1(4) and 1(5)). The specific
resistance of the indium oxide-tin oxide-samarium oxide layer was
720 .mu..OMEGA.cm, and the electrode resistance was 1.47
k.OMEGA..
[0212] The thus obtained semi-transparent semi-reflective electrode
substrate had low electric resistance. The surface of the substrate
was observed with a scanning electron microscope, and as a result
no surface roughness was observed on the metal oxide layer 12. In
addition, changes in the edges of the inorganic compound layer 14
were hardly seen before and after etching with oxalic acid. This
means that the inorganic compound layer 14 was hardly etched with
an etchant .sigma. containing oxalic acid.
[0213] It is to be noted that the ratio of the etching rate of the
inorganic compound layer 14 to that of the metal oxide layer 12 was
20.
COMPARATIVE EXAMPLE 1-1
[0214] A metal oxide layer 12 and an inorganic compound layer 14
were formed in the same manner as in Example 1-1 except that the
first target was changed to the seventh target composed of indium
oxide-tin oxide (In/(In+Sn)=90 atomic %).
[0215] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate. The specific resistance of the indium
oxide-tin oxide layer was 250 .mu..OMEGA.cm.
[0216] Surface roughness due to the etchant was hardly observed on
the thus obtained semi-transparent semi-reflective electrode
substrate. However, it was impossible to etch the metal oxide layer
12 with oxalic acid.
Comparative Example 1-2
[0217] A metal oxide layer 12 and an inorganic compound layer 14
were formed in the same manner as in Example 1-1 except that the
first target was changed to the eighth target composed of indium
oxide-zinc oxide (In/(In+Zn)=85 atomic %).
[0218] Next, etching was carried out in the same manner as in
Example 1-1 to manufacture a semi-transparent semi-reflective
electrode substrate. The specific resistance of the indium
oxide-zinc oxide layer was 390 .mu..OMEGA.cm.
[0219] In this case, the indium oxide-zinc oxide layer was also
etched when Ag was etched.
[0220] (Summary of the First Embodiment)
[0221] As described above, according to the present invention, it
is possible to avoid a repetition of complicated operations by
using an etchant which enables selective etching, that is, by using
an etchant having different etching rates for different layers,
thereby simplifying the manufacturing processes of a
semi-transparent semi-reflective electrode substrate and shortening
the manufacturing time thereof. Therefore, it is possible to
efficiently provide a semi-transparent semi-reflective electrode
substrate.
[0222] Second Embodiment
[0223] Hereinbelow, a preferred second embodiment according to the
present invention will be described. It is to be noted that in the
present invention, the word "batch etching" means that an inorganic
compound layer and a metal oxide layer are subjected to etching at
a time with a single etchant.
EXAMPLE 2-1
[0224] (a) Inorganic Compound Layer and Metal Oxide Layer
[0225] (1) Formation of Inorganic Compound Layer and Measurement of
Etching Rate
[0226] A blue plate glass substrate coated with SiO.sub.2 was
placed in a DC magnetron sputtering system (manufactured by Anelva
Corporation), and the blue plate glass substrate was heated to
200.degree. C. Then, sputtering was carried out using an Al target
(Al: 100 atomic %) to form an inorganic compound layer having a
thickness of 100 nm on the blue plate glass substrate.
[0227] An etchant containing phosphoric acid (40 wt %), nitric acid
(2.5 wt %), and acetic acid (40 wt %) (hereinafter, simply referred
to as an "etchant (I)") was prepared, and then the inorganic
compound layer provided on the blue plate glass substrate was
subjected to etching with the etchant (I) at 30.degree. C. At this
time, the etching rate A(I) of the inorganic compound layer was
measured, and was found to be 42 nm/min.
[0228] On the other hand, another etchant containing phosphoric
acid (55 wt %), nitric acid (2.5 wt %), and acetic acid (40 wt %)
(hereinafter, simply referred to as an "etchant (II)") was
prepared, and then the inorganic compound layer provided on another
blue plate glass substrate was subjected to etching with the
etchant (II) at 30.degree. C. At this time, the etching rate A(II)
of the inorganic compound layer was measured, and was found to be
73 nm/min.
[0229] (2) Formation of Metal Oxide Layer and Measurement of
Etching Rate
[0230] In the same manner as in (a)(1) described above, a blue
plate glass substrate coated with SiO.sub.2 was placed in the DC
magnetron sputtering system, and the blue plate glass substrate was
heated to 200.degree. C. Then, sputtering was carried out using an
indium oxide-zinc oxide target ([In]:[Zn]=83.0:17.0 atomic %) to
form a metal oxide layer having a thickness of 75 nm on the blue
plate glass substrate.
[0231] The metal oxide layer provided on the blue plate glass
substrate was subjected to etching with the etchant (I) at
30.degree. C. At this time, the etching rate B(I) of the metal
oxide layer was measured, and was found to be 41 nm/min.
[0232] On the other hand, the metal oxide layer provided on another
blue plate glass substrate was subjected to etching with the
etchant (II) at 30.degree. C. At this time, the etching rate B(II)
of the metal oxide layer was measured, and was found to be 42
nm/min.
[0233] (3) Calculation of Etching Rate Ratio
[0234] The ratio between the etching rate of the inorganic compound
layer and that of the metal oxide layer, that is, B(I)/A(I) and
B(II)/A(II) were calculated from the etching rates A(I), A(II),
B(I), and B(II) measured in (a)(1) and (a)(2). As a result,
B(I)/A(I) was 0.98 and B(II)/A(II) was 0.58 (see Table 2-1).
[0235] (4) Measurement of Work Function and Specific Resistance of
Metal Oxide Layer
[0236] The metal oxide layer provided on the blue plate glass
substrate was cleaned by the application of X rays. Then, the work
function of the metal oxide layer was measured with a photoelectron
spectrometer ("AC-1" manufactured by Riken Keiki Co., Ltd.),and was
found to be 5.24 eV (see Table 2-2). Further, the specific
resistance of the metal oxide layer was measured with a resistivity
meter ("Loresta" manufactured by Mitsubishi Yuka K.K.), and was
found to be 340 .mu..OMEGA.cm (see Table 2-2).
[0237] (b) Reflective Electrode Substrate
[0238] (1) Manufacture of Reflective Electrode Substrate
[0239] As shown in FIG. 8(1), in the same manner as in (a)(1), a
blue plate glass substrate 210 coated with SiO.sub.2 was placed in
the DC magnetron sputtering system, and the blue plate glass
substrate 210 was heated to 200.degree. C. As shown in FIG. 8(2),
sputtering was carried out using an Al target (Al: 100 atomic %) to
form an inorganic compound layer 211 having a thickness of 100 nm
on the blue plate glass substrate 210. As shown in FIG. 8(3),
sputtering was then carried out using an indium oxide-zinc oxide
target ([In]:[Zn]=83.0:17.0 atomic %) to form a metal oxide layer
212 having a thickness of 20 nm on the inorganic compound layer 211
provided on the blue plate glass substrate 210. In this way, an
electrode layer 213 composed of the inorganic compound layer 211
and the metal oxide layer 212 was formed on the blue plate glass
substrate 210 to manufacture a reflective electrode substrate 201.
The surface resistivity of the reflective electrode substrate 201
was measured with a surface resistivity meter similar to the
resistivity meter used in (a)(4), and was found to be 1.2
.OMEGA..quadrature. (see Table 2-2)
[0240] (2) Analysis of Etching Characteristics of Reflective
Electrode Substrate
[0241] Onto the metal oxide layer 212 of the reflective electrode
substrate 201, a resist ("NPR2048USP" manufactured by Nippon
Polytech Corporation) was applied, and then the resist was exposed
to X rays through a photomask. After development, the resist was
heated to 130.degree. C., and was then post-baked for 15 minutes.
In this way, a resist mask 214 was formed on the metal oxide layer
212 (see FIG. 8(4)).
[0242] The inorganic compound layer 211 and the metal oxide layer
212 of the reflective electrode substrate 201 were subjected to
batch etching using the etchant (I) and the etchant (II) to obtain
a reflective electrode substrate 201 as shown in FIG. 9.
[0243] The etched surface of the inorganic compound layer 211 and
the etched surface of the metal oxide layer 212 were observed with
a scanning electron microscope ("S800" manufactured by Hitachi
Ltd.). As a result, no residue was left on the etched surfaces, and
the etched surfaces were smooth with no steps. Further, the
inorganic compound layer 211 and the metal oxide layer 212 were
well etched in accordance with the pattern of the resist mask 214
(see Table 2-2).
EXAMPLES 2-2 to 2-14
[0244] (a) Inorganic Compound Layer and Metal Oxide Layer
[0245] (1) Formation of Inorganic Compound Layer and Measurement of
Etching Rate
[0246] In the same manner as in Example 2-1 (a)(1) , an inorganic
compound layer was formed on a blue plate glass substrate, and then
the etching rates A(I) and A(II) of the inorganic compound layer
were measured. The etching rates A(I) and A(II) were the same as
those measured in Example 2-1 (a)(1).
[0247] (2) Formation of Metal Oxide Layer and Measurement of
Etching Rate
[0248] A metal oxide layer was formed on a blue plate glass
substrate in the same manner as in Example 2-1 (a)(2) except that
the indium oxide-zinc oxide target ([In]:[Zn]=83.0:17.0 atomic %)
was changed to a target with the composition shown in Table
2-1.
[0249] As shown in Table 2-1, targets used in Examples 2-2 to
2-14are slightly different from each other. Specifically, each of
the targets used in Examples 2-2 to 2-14 contains a lanthanoid
group metal element as a third element in addition to indium and
zinc. The composition of each of the targets used in Examples 2-2
to 2-14 is expressed in terms of atomic % in Table 2-1. Therefore,
Examples 2-2 to 2-14 are different from each other in the
composition of a target for use in sputtering the metal oxide
layer. In each of Examples 2-2 to 2-14, the physical properties of
the metal oxide layer were measured.
[0250] The metal oxide layer provided on the blue plate glass
substrate was subjected to etching with the etchant (I) at
30.degree. C. At this time, the etching rate B(I) of the metal
oxide layer was measured. On the other hand, the metal oxide layer
provided on another blue plate glass substrate was subjected to
etching with the etchant (II) at 30.degree. C. At this time, the
etching rate B(II) of the metal oxide layer was measured.
[0251] (3) Calculation of Etching Rate Ratio
[0252] The ratio between the etching rate of the inorganic compound
layer and that of the metal oxide layer, that is, B(I)/A(I) and
B(II)/A(II) were calculated from the etching rates A(I), A(II),
B(I), and B(II) measured in (a)(1) and (a)(2). The calculation
results are shown in Table 2-1.
[0253] (4) Measurement of Work Function and Specific Resistance of
Metal Oxide Layer
[0254] In the same manner as in Example 2-1 (a)(4), the metal oxide
layer provided on the blue plate glass substrate was cleaned by the
application of X rays, and then the work function and the specific
resistance of the metal oxide layer were measured. The measurement
results are shown in Table 2-2.
[0255] (b) Reflective Electrode Substrate
[0256] (1) Manufacture of Reflective Electrode Substrate
[0257] In each of Examples 2-2 to 2-14, an inorganic compound layer
211 and a metal oxide layer 212 were formed on a blue plate glass
substrate 210 in the same manner as in Example 2-1 (b)(1) except
that the indium oxide-zinc oxide target ([In]:[Zn]=83.0:17.0 atomic
%) used for sputtering was changed to a target with the composition
shown in Table 2-1 (see FIG. 8(3)). In this way, a reflective
electrode substrate 201 having an electrode layer 213 composed of
the inorganic compound layer 211 and the metal oxide layer 212 was
manufactured. The surface resistivity of the reflective electrode
substrate 201 was measured with a surface resistivity meter similar
to the resistivity meter used in Example 2-1 (see Table 2-2).
[0258] In each of Examples 2-2 to 2-14, a resist mask 214 was
formed on the metal oxide layer 212 of the reflective electrode
substrate 201 in the same manner as in Example 2-1 (b)(2)(see FIG.
8(4)). Then, the inorganic compound layer 211 and the metal oxide
layer 212 of the reflective electrode substrate 201 were subjected
to batch etching using the etchant (I) and the etchant (II) to
obtain a reflective electrode substrate 201 as shown in FIG. 9.
[0259] (2) Analysis of Etching Characteristics of Reflective
Electrode Substrate
[0260] The etched surface of the inorganic compound layer 211 and
the etched surface of the metal oxide layer 212 were observed with
the same scanning electron microscope as used in Example 2-1. As a
result, in all the reflective electrode substrates of Examples 2-2
to 2-14, no residue was left on the etched surfaces, and the etched
surfaces were smooth with no steps. Further, the inorganic compound
layer 211 and the metal oxide layer 212 were well etched in
accordance with the pattern of the resist mask 214 (see Table 2-2).
TABLE-US-00001 TABLE 2-1 Composition of target Inorganic compound
layer Metal oxide layer Al [In] [Zn] Third ingredient Etching rate
ratio Examples (atomic %) (atomic %) (atomic %) (atomic %)
B(I)/A(I) *.sup.) B(II)/A(II) **.sup.) 2-1 100 83.0 17.0 0.98 0.58
2-2 100 80.7 14.4 [Ce](4.9) 0.99 0.58 2-3 100 74.0 11.5 [Pr](14.5)
1.01 0.62 2-4 100 84.1 14.8 [Nd](1.1) 1.02 0.59 2-5 100 81.6 14.7
[Sm](3.7) 1.00 0.60 2-6 100 82.5 14.9 [Eu](2.6) 1.00 0.61 2-7 100
83.3 14.5 [Gd](1.2) 1.07 0.66 2-8 100 79.0 14.3 [Tb](6.7) 1.00 0.62
2-9 100 72.0 15.0 [Dy](13.9) 1.00 0.62 2-10 100 78.2 15.2 [Ho](6.6)
1.02 0.62 2-11 100 78.0 16.7 [Er](5.3) 1.02 0.62 2-12 100 77.0 17.7
[Tm](5.3) 1.02 0.62 2-13 100 79.8 16.8 [Yb](3.4) 1.02 0.62 2-14 100
82.5 14.7 [Lu](2.8) 1.02 0.62 *.sup.) A(I): A(I) represents the
etching rate of the inorganic compound layer with the etchant (I)
containing phosphate ions (40 wt %), nitrate ions (2.5 wt %), and
acetate ions (40 wt %) at 30o C.. B(I): B(I) represents the etching
rate of the metal oxide layer with the etchant (I) containing
phosphate ions (40 wt %), nitrate ions (2.5 wt %), and acetate ions
(40 wt %) at 30.degree. C.. **.sup.) A(II): A(II) represents the
etching rate of the inorganic compound layer with the etchant (II)
containing phosphate ions (55 wt %), nitrate ions (2.5 wt %), and
acetate ions (40 wt %) at 30.degree. C.. B(II): B(II) represents
the etching rate of the metal oxide layer with the etchant (II)
containing phosphate ions (55 wt %), nitrate ions (2.5 wt %), and
acetate ions (40 wt %) at 30.degree. C..
[0261] TABLE-US-00002 TABLE 2-2 Metal oxide layer Reflective
electrode substrate Specific Surface Etched Work resistance
resistivity surface Examples function (eV) (.mu..OMEGA.cm)
(.OMEGA./.quadrature.) condition 2-1 5.24 340 1.2 Good 2-2 5.92 960
1.2 Good 2-3 5.88 860 1.2 Good 2-4 5.61 650 1.2 Good 2-5 5.74 480
1.2 Good 2-6 5.68 730 1.2 Good 2-7 5.60 530 1.2 Good 2-8 5.63 1950
1.2 Good 2-9 5.58 980 1.2 Good 2-10 5.56 475 1.2 Good 2-11 5.48 460
1.2 Good 2-12 5.28 420 1.2 Good 2-13 5.34 455 1.2 Good 2-14 5.28
415 1.2 Good
EXAMPLE 2-15
[0262] (a) Inorganic Compound Layer and Metal Oxide Layer
[0263] (1) Formation of Inorganic Compound Layer and Measurement of
Etching Rate
[0264] An inorganic compound layer was formed on a blue plate glass
substrate in the same manner as in Example 2-1 (a)(1) except that
the Al target (Al: 100 atomic %) used for sputtering was changed to
an Al--Au target ([Al]:[Au]=99:1 atomic %).
[0265] The inorganic compound layer provided on the blue plate
glass substrate was subjected to etching with the etchant (I) at
30.degree. C. At this time, the etching rate A(I) of the inorganic
compound layer was measured, and was found to be 38 nm/min. On the
other hand, the inorganic compound layer provided on another blue
plate glass substrate was subjected to etching with the etchant
(II) at 30.degree. C. At this time, the etching rate A(II) of the
inorganic compound layer was measured, and was found to be 71
nm/min.
[0266] (2) Formation of Metal Oxide Layer and Measurement of
Etching Rate, Work Function, and Specific Resistance
[0267] In the same manner as in Example 2-1 (a)(2) , a metal oxide
layer was formed on a blue plate glass substrate, and then the
etching rates B(I) and B(II) of the metal oxide layer were
measured. The measurement results were the same as those measured
in Example 2-1 (a)(2). Further, in the same manner as in Example
1-2 (a)(4), the work function and the specific resistance of the
metal oxide layer were measured. The measurement results were the
same as those measured in Example 1-2 (a)(4).
[0268] (3) Calculation of Etching Rate Ratio
[0269] The ratio between the etching rate of the inorganic compound
layer and that of the metal oxide layer, that is, B(I)/A(I) and
B(II)/A(II) were calculated from the etching rates A(I), A(II),
B(I), and B(II) measured in (a)(1) and (a)(2). As a result,
B(I)/A(I) was 1.08, and B(II)/A(II) was 0.59 (see Table 2-3).
[0270] (b) Reflective Electrode Substrate
[0271] (1) Manufacture of Reflective Electrode Substrate
[0272] An inorganic compound layer 211 and a metal oxide layer 212
were formed on a blue plate glass substrate 210 in the same manner
as in Example 2-1 (b)(1) except that the Al target (Al: 100 atomic
%) used for sputtering was changed to an Al--Au target
([Al]:[Au]=99:1atomic %). In this way, a reflective electrode
substrate 201 having an electrode layer 213 composed of the
inorganic compound layer 211 and the metal oxide layer 212 was
manufactured (see FIG. 8(3)). The surface resistivity of the
reflective electrode substrates 201 was measured with a surface
resistivity meter similar to that used in Example 2-1 (b)(1), and
was found to be 1.2 .OMEGA./.quadrature. (see Table 2-3).
[0273] A resist mask 214 was formed on the metal oxide layer 212 of
the reflective electrode substrate 201 in the same manner as in
Example 2-1 (b)(2) (see FIG. 8(4)). Then, the inorganic compound
layer 211 and the metal oxide layer 212 of the reflective electrode
substrate 201 were subjected to batch etching using the etchant (I)
and the etchant (II) to obtain a reflective electrode substrate 201
as shown in FIG. 9.
[0274] (2) Analysis of Etching Characteristics of Reflective
Electrode Substrate
[0275] The etched surface of the inorganic compound layer 211 and
the etched surface of the metal oxide layer 212 were observed with
the same scanning electron microscope as used in Example 2-1
(b)(2). As a result, no residue was left on the etched surfaces,
and the etched surfaces were smooth with no steps. Further, the
inorganic compound layer 211 and the metal oxide layer 212 were
well etched in accordance with the pattern of the resist mask 214
(see Table 2-3).
EXAMPLE 2-16
[0276] (a) Inorganic Compound Layer and Metal Oxide Layer
[0277] (1) Formation of Inorganic Compound Layer and Measurement of
Etching Rate
[0278] An inorganic compound layer was formed on a blue plate glass
substrate in the same manner as in Example 2-1 (a)(1) except that
the Al target (Al: 100 atomic %) used for sputtering was changed to
an Al--Pt target ([Al]:[Pt]=99:1 atomic %).
[0279] The inorganic compound layer provided on the blue plate
glass substrate was subjected to etching with the etchant (I) at
30.degree. C. At this time, the etching rate A(I) of the inorganic
compound layer was measured, and was found to be 39 nm/min. On the
other hand, the inorganic compound layer provided on another blue
plate glass substrate was subjected to etching with the etchant
(II) at 30.degree. C. At this time, the etching rate A(II) of the
inorganic compound layer was measured, and was found to be 69
nm/min.
[0280] (2) Formation of Metal Oxide Layer and Measurement of
Etching Rate, Work Function, and Specific Resistance
[0281] In the same manner as in Example 2-1 (a)(2) , a metal oxide
layer was formed on a blue plate glass substrate, and then the
etching rates B(I) and B(II) of the metal oxide layer were
measured. The measurement results were the same as those measured
in Example 2-1 (a)(2). Further, in the same manner as in Example2-1
(a)(4), the work function and the specific resistance of the metal
oxide layer were measured. The measurement results were the same as
those measured in Example 2-1 (a)(4).
[0282] (3) Calculation of Etching Rate Ratio
[0283] The ratio between the etching rate of the inorganic compound
layer and that of the metal oxide layer, that is, B(I)/A(I) and
B(II)/A(II) were calculated from the etching rates A(I), A(II),
B(I), and B(II) measured in (a)(1) and (a)(2). As a result,
B(I)/A(I) was 1.05, and B(II)/A(II) was 0.61 (see Table 2-3).
[0284] (b) Reflective Electrode Substrate
[0285] (1) Manufacture of Reflective Electrode Substrate
[0286] An inorganic compound layer 211 and a metal oxide layer 212
were formed on a blue plate glass substrate 210 in the same manner
as in Example 2-1 (b)(1) except that the Al target (Al: 100 atomic
%) used for sputtering was changed to an Al--Pt target
([Al]:[Pt]=99:1 atomic %). In this way, are a reflective electrode
substrate 201 having an electrode layer 213 composed of the
inorganic compound layer 211 and the metal oxide layer 212 was
manufactured (see FIG. 8(3)). The surface resistivity of the
reflective electrode substrates 201 was measured with a surface
resistivity meter similar to that used in Example 2-1 (b)(1), and
was found to be 1.2 .OMEGA./.quadrature. (see Table 2-3).
[0287] A resist mask 214 was formed on the metal oxide layer 212 of
the reflective electrode substrate 201 in the same manner as in
Example 2-1 (b)(2) (see FIG. 8(4)). Then, the inorganic compound
layer 211 and the metal oxide layer 212 of the reflective electrode
substrate 201 were subjected to batch etching using the etchant (I)
and the etchant (II) to obtain a reflective electrode substrate 201
as shown in FIG. 9.
[0288] (2) Analysis of Etching Characteristics of Reflective
Electrode Substrate
[0289] The etched surface of the inorganic compound layer 211 and
the etched surface of the metal oxide layer 212 were observed with
the same scanning electron microscope as used in Example 2-1
(b)(2). As a result, no residue was left on the etched surfaces,
and the etched surfaces were smooth with no steps. Further, the
inorganic compound layer 211 and the metal oxide layer 212 were
well etched in accordance with the pattern of the resist mask 214
(see Table 2-3).
EXAMPLE 2-17
[0290] (a) Inorganic Compound Layer and Metal Oxide Layer
[0291] (1) Formation of Inorganic Compound Layer and Measurement of
Etching rate
[0292] An inorganic compound layer was formed on a blue plate glass
substrate in the same manner as in Example 2-1 (a)(1) except that
the Al target (Al: 100 atomic %) used for sputtering was changed to
an Al--Nd target ([Al]:[Nd]=99:1 atomic %).
[0293] The inorganic compound layer provided on the blue plate
glass substrate was subjected to etching with the etchant (I) at
30.degree. C. At this time, the etching rate A(I) of the inorganic
compound layer was measured, and was found to be 41 nm/min. On the
other hand, the inorganic compound layer provided on another blue
plate glass substrate was subjected to etching with the etchant
(II) at 30.degree. C. At this time, the etching rate A(II) of the
inorganic compound layer was measured, and was found to be 71
nm/min.
[0294] (2) Formation of Metal Oxide Layer and Measurement of
Etching Rate, Work Function, and Specific Resistance
[0295] In the same manner as in Example 2-1 (a)(2), a metal oxide
layer was formed on a blue plate glass substrate, and then the
etching rates B(I) and B(II) of the metal oxide layer were
measured. The measurement results were the same as those measured
in Example 2-1 (a)(2). Further, in the same manner as in Example
2-1 (a)(4), the work function and the specific resistance of the
metal oxide layer were measured. The measurement results were the
same as those measured in Example 2-1 (a)(4).
[0296] (3) Calculation of Etching Rate Ratio
[0297] The ratio between the etching rate of the inorganic compound
layer and that of the metal oxide layer, that is, B(I)/A(I) and
B(II)/A(II) were calculated from the etching rates A(I), A(II),
B(I), and B(II) measured in (a)(1) and (a)(2). As a result,
B(I)/A(I) was 1.00 and B(II)/A(II) was 0.59 (see Table 2-3).
[0298] (b) Reflective Electrode Substrate
[0299] (1) Manufacture of Reflective Electrode Substrate
[0300] An inorganic compound layer 211 and a metal oxide layer 212
were formed on a blue plate glass substrate 210 in the same manner
as in Example 2-1 (b)(1) except that the Al target (Al: 100 atomic
%) used for sputtering was changed to an Al--Nd target
([Al]:[Nd]=99:1 atomic %). In this way, a reflective electrode
substrate 201 having an electrode layer 213 composed of the
inorganic compound layer 211 and the metal oxide layer 212 was
manufactured (see FIG. 8(3)). The surface resistivity of the
reflective electrode substrates 201 was measured with a surface
resistivity meter similar to that used in Example 2-1 (b)(1), and
was found to be 1.2 .OMEGA./.quadrature. (see Table 2-3).
[0301] A resist mask 214 was formed on the metal oxide layer 212 of
the reflective electrode substrate 201 in the same manner as in
Example 2-1 (b)(2) (see FIG. 8(4)). Then, the inorganic compound
layer 211 and the metal oxide layer 212 of the reflective electrode
substrate 201 were subjected to batch etching using the etchant (I)
and the etchant (II) to obtain a reflective electrode substrate 201
as shown in FIG. 9.
[0302] (2) Analysis of Etching Characteristics of Reflective
Electrode Substrate
[0303] The etched surface of the inorganic compound layer 211 and
the etched surface of the metal oxide layer 212 were observed with
the same scanning electron microscope as used in Example 2-1
(b)(2). As a result, no residue was left on the etched surfaces,
and the etched surfaces were smooth with no steps. Further, the
inorganic compound layer 211 and the metal oxide layer 212 were
well etched in accordance with the pattern of the resist mask 214
(see Table 2-3). TABLE-US-00003 TABLE 2-3 Composition of target
Inorganic Reflective electrode compound layer substrate Second
Metal oxide layer Surface Etched [Al] ingredient [In] [Zn]
resistivity surface Etching rate ratio Examples (atomic %) (atomic
%) (atomic %) (atomic %) (.OMEGA./.quadrature.) condition
B(I)/A(I)* B(II)/A(II)* 2-15 99 [Au](1) 83.0 17.0 1.2 Good 1.08 059
2-16 99 [Pt](1) 83.0 17.0 1.2 Good 1.08 0.61 2-17 99 [Nd](1) 83.0
17.0 1.2 Good 1.08 0.59 *A(I): A(I) represents the etching rate of
the inorganic compound layer with the etchant (I) containing
phosphoric acid (40 wt %), nitric acid (2.5 wt %), and acetic acid
(40 wt %) at 30.degree. C.. B(I): B(I) represents the etching rate
of the metal oxide layer with the etchant (I) containing phosphoric
acid (40 wt %), nitric acid (2.5 wt %), and acetic acid (40 wt %)
at 30.degree. C.. ** A(II): A(II) represents the etching rate of
the inorganic compound layer with the etchant (II) containing
phosphoric acid (55 wt %), nitric acid (2.5 wt %), and acetic acid
(40 wt %) at 30.degree. C.. B(II): B(II) represents the etching
rate of the metal oxide layer with the etchant (II) containing
phosphoric acid (55 wt %), nitric acid (2.5 wt %), and acetic acid
(40 wt %) at 30.degree. C..
CONPARATIVE EXAMPLE 2-1
[0304] (a) Inorganic Compound Layer and Metal Oxide Layer
[0305] (1) Formation of Inorganic Compound Layer and Measurement of
Etching Rate
[0306] In the same manner as in Example 2-1 (a)(1), an inorganic
compound layer was formed on a blue plate glass substrate, and then
the etching rates A(I) and A(II) of the inorganic compound layer
were measured. The measurement results were the same as those
measured in Example 2-1 (a)(1).
[0307] (2) Formation of Metal Oxide Layer and Analysis of Etching
Characteristics
[0308] A metal oxide layer was formed on a blue plate glass
substrate in the same manner as in Example 2-1 (a)(2) except that
the indium oxide-zinc oxide target ([In]:[Zn]=83.0:17.0 atomic %)
used for sputtering was changed to an indium oxide-tin oxide target
([In]:[Sn]=85.0:15.0 atomic %) (see Table 2-4).
[0309] Then, in the same manner as in Example 2-1 (a)(4), the metal
oxide layer was cleaned with X rays to measure the work function of
the metal oxide layer. The work function of the metal oxide layer
was 5.12 eV (see Table 2-5). Further, in the same manner as in
Example 2-1 (a)(4), the specific resistance of the metal oxide
layer was measured, and was found to be 210 .mu..OMEGA.cm (see
Table 2-5).
[0310] Next, the metal oxide layer provided on the blue plate glass
substrate was subjected to batch etching using the etchant (I). On
the other hand, the metal oxide layer provided on another blue
plate glass substrate was subjected to batch etching using the
etchant (II). In either case, the metal oxide layer was not
dissolved (see Tables 2-4 and 2-5).
COMPARATIVE EXAMPLE 2-2
[0311] (a) Inorganic Compound Layer and Metal Oxide Layer
[0312] (1) Formation of Inorganic Compound Layer and Measurement of
Etching Rate
[0313] In the same manner as in Example 2-1 (a)(1) , an inorganic
compound layer was formed on a blue plate glass substrate, and then
the etching rates A(I) and A(II) of the inorganic compound layer
were measured. The measurement results were the same as those
measured in Example 2-1 (a)(1).
[0314] (2) Formation of Metal Oxide Layer and Measurement of
Etching Rate
[0315] A metal oxide layer was formed on a blue plate glass
substrate in the same manner as in Example 2-1 (a)(2) except that
the indium oxide-zinc oxide target ([In]:[Zn]=83.0:17.0 atomic %)
used for sputtering was changed to an indium oxide-tin oxide-cerium
oxide target ([In]:[Sn]:[Ce]=85.0:10.0:5.0 atomic %).
[0316] The metal oxide layer provided on the blue plate glass
substrate was subjected to etching with the etchant (I) at
30.degree. C. At this time, the etching rate B(I) of the metal
oxide layer was measured, and was found to be 7.6 nm/min. On the
other hand, the metal oxide layer provided on another blue plate
glass substrate was subjected to etching with the etchant (II) at
30.degree. C. At this time, the etching rate B(II) of the metal
oxide layer was measured, and was found to be 5.1 nm/min.
[0317] (3) Calculation of Etching Rate Ratio
[0318] The ratio between the etching rate of the inorganic compound
layer and that of the metal oxide layer, that is, B(I)/A(I) and
B(II)/A(II) were calculated from the etching rates A(I), A(II),
B(I), and B(II) measured in (a)(1) and (a)(2). As a result,
B(I)/A(I) was 0.18 and B(II)/A(II) was 0.07 (see Table 2-4).
[0319] (4) Measurement of Work Function and Specific Resistance of
Metal Oxide Layer
[0320] In the same manner as in Example 2-1 (a)(4), the metal oxide
layer provided on the blue plate glass substrate was cleaned with X
rays to measure the work function of the metal oxide layer. The
work function of the metal oxide layer was 5.88 eV (see Table 2-5).
Further, in the same manner as in Example 2-1 (a)(4), the specific
resistance of the metal oxide layer was measured, and was found to
be 780 .mu..OMEGA.cm (see Table 2-5).
[0321] (b) Reflective Electrode Substrate
[0322] (1) Manufacture of Reflective Electrode Substrate
[0323] An inorganic compound layer 211 and a metal oxide layer 212
were formed on a blue plate glass substrate 210 in the same manner
as in Example 2-1 (b)(1) except that the indium oxide-zinc oxide
target ([In]:[Zn]=87.0:13.0 atomic %) used for sputtering was
changed to an indium oxide-tin oxide-cerium oxide target
([In]:[Sn]:[Ce]=85.0:10.0:5.0 atomic %) (see Table 2-4). In this
way, a reflective electrode substrate 201 having an electrode layer
213 composed of the inorganic compound layer 211 and the metal
oxide layer 212 was manufactured (see FIG. 8(3)).
[0324] In the same manner as in Example 2-1 (b)(2), a resist mask
214 was formed on the metal oxide layer 212 of the reflective
electrode substrate 201 (see FIG. 8(4)). Then, the inorganic
compound layer 211 and the metal oxide layer 212 of the reflective
electrode substrate 201 were subjected to batch etching using the
etchant (I) and the etchant (II).
[0325] (2) Analysis of Etching Characteristics of Reflective
Electrode Substrate
[0326] The etched surface of the inorganic compound layer 211 and
the etched surface of the metal oxide layer 212 were observed with
the same scanning electron microscope as used in Example 2-1. As a
result, a large step was observed at the boundary between the
inorganic compound layer 211 and the metal oxide layer 212 (see
Table 2-5). TABLE-US-00004 TABLE 2-4 Composition of target
Inorganic compound layer Metal oxide layer Comparative [Al] [In]
[Sn] Third ingredient Etching rate ratio Examples (atomic %)
(atomic %) (atomic %) (atomic %) B(I)/A(I)* B(II)/A(II)* 2-1 100
85.0 15.0 -- The metal oxide layer could not be etched. 2-2 100
85.0 10.0 [Ce](5.0) 0.18 0.07 *A(I): A(I) represents the etching
rate of the inorganic compound layer with the etchant (I)
containing phosphoric acid (40 wt %), nitric acid (2.5 wt %), and
acetic acid (40 wt %) at 30.degree. C.. B(I): B(I) represents the
etching rate of the metal oxide layer with the etchant (I)
containing phosphoric acid (40 wt %), nitric acid (2.5 wt %), and
acetic acid (40 wt %) at 30.degree. C.. ** A(II): A(II) represents
the etching rate of the inorganic compound layer with the etchant
(II) containing phosphoric acid (55 wt %), nitric acid (2.5 wt %),
and acetic acid (40 wt %) at 30.degree. C.. B(II): B(II) represents
the etching rate of the metal oxide layer with the etchant (II)
containing phosphoric acid (55 wt %), nitric acid (2.5 wt %), and
acetic acid (40 wt %) at 30.degree. C..
[0327] TABLE-US-00005 TABLE 2-5 Work Specific Comparative function
resistance Examples (eV) (.mu..OMEGA.cm) Etched surface condition
2-1 5.12 210 The metal oxide layer could not be etched. 2-2 5.88
780 The inorganic compound layer was over-etched so that a large
step was produced.
[0328] As described above, according to the manufacturing method of
Comparative Example, it is difficult to carry out etching without
producing a step at the boundary between the metal oxide layer and
the inorganic compound layer. Therefore, it can be considered that
it is also difficult to manufacture a reflective electrode
substrate having a low specific resistance and a high work function
by the manufacturing method according to Comparative Example. It is
to be noted that all of the electrode layers of Examples 2-1 to
2-17 had a high reflectivity.
[0329] (Summary of the Second Embodiment)
[0330] As described above, according to the manufacturing method of
the present invention, it is possible to obtain a reflective
electrode substrate having a low specific resistance and a high
work function because the inorganic compound layer contains at
least Al and the metal oxide layer contains at least indium oxide.
Further, by using an etchant containing an etching composition
composed of phosphoric acid, nitric acid, and acetic acid, it is
also possible to subject the metal oxide layer and the inorganic
compound layer to batch etching. In the thus obtained reflective
electrode substrate according to the present invention, there is
substantially no step at the boundary between the metal oxide layer
and the inorganic compound layer, and there is little residue on
the etched surface.
[0331] Third Embodiment
[0332] Hereinbelow, a third embodiment according to the present
invention will be described with reference to examples of the third
embodiment. However, the present invention is not limited to these
examples.
EXAMPLE 3-1
[0333] (a) Formation of Metal Oxide Layer and Measurement of Work
Function and Specific Resistance
[0334] (1) Formation of Metal Oxide Layer
[0335] A blue plate glass substrate coated with SiO.sub.2was
prepared, and was heated to 200.degree. C. Then, sputtering was
carried out using an indium oxide-zinc oxide-cerium oxide target
([In]:[Zn]:[Ce]=80.7:14.4:4.9 atomic %) to form a metal oxide layer
having a thickness of 100 nm on the blue plate glass substrate.
[0336] (2) Measurement of Work Function and Specific Resistance of
Metal Oxide Layer
[0337] The metal oxide layer provided on the blue plate glass
substrate was cleaned by the application of X rays. Then, the work
function of the metal oxide layer was measured with a photoelectron
spectrometer ("AC-1" manufactured by Riken Keiki Co., Ltd.), and
was found to be 5.92 eV (see Table 3-1). Further, the specific
resistance of the metal oxide layer was measured with a resistivity
meter ("Loresta" manufactured by Mitsubishi Yuka K.K.), and was
found to be 960 .mu..OMEGA.cm (see Table 3-1).
[0338] (b) Manufacture of Reflective Electrode Substrate,
Measurement of Surface Resistivity, and Analysis of Etching
Characteristics
[0339] (1) Manufacture of Reflective Electrode Substrate
[0340] As shown in FIG. 10(1), in the same manner as in (a)(1), a
blue plate glass substrate 310 coated with SiO.sub.2 was heated to
200.degree. C. Then, sputtering was carried out using an Ag target
(Ag:100 atomic %) to form an inorganic compound layer 311 having a
thickness of 100 nm on the blue plate glass substrate 310 (see FIG.
10(2)). Next, sputtering was carried out using an indium oxide-zinc
oxide-cerium oxide target ([In]:[Zn]:[Ce]=80.7:14.4:4.9 atomic %)
to form a metal oxide layer 312 having a thickness of 20 nm on the
inorganic compound layer 311 provided on the blue plate glass
substrate 310 (see FIG. 10(3)). In this way, an electrode layer 313
composed of the inorganic compound layer 311 and the metal oxide
layer 312 was formed on the blue plate glass substrate 310 to
obtain a reflective electrode substrate 301.
[0341] (2) Measurement of Surface Resistivity
[0342] The surface resistivity of the reflective electrode
substrate 301 was measured with a surface resistivity meter similar
to the resistivity meter used in (a)(2), and was found to be 1.2
.OMEGA./.quadrature..
[0343] (3) Analysis of Etching Characteristics
[0344] Onto the metal oxide layer 312 of the reflective electrode
substrate 301, a resist ("NPR2048USP" manufactured by Nippon
Polytech Corporation) was applied, and then the resist was exposed
to X rays through a photomask. After development, the resist was
heated to 130.degree. C., and was then post-baked for 15 minutes.
In this way, a resist mask 314 was formed on the metal oxide layer
312 (see FIG. 10(4)).
[0345] The metal oxide layer 312 provided on the blue plate glass
substrate 310 was subjected to etching with an aqueous oxalic acid
solution (3.5 wt %) at 30.degree. C. Next, the inorganic compound
layer 311 was subjected to etching with an etchant containing
phosphoric acid (30 wt %), nitric acid (1.5 wt %), and acetic acid
(40 wt %) at 30.degree. C. In this way, a reflective electrode
substrate 301 shown in FIG. 11 was obtained.
[0346] The etched surface of the inorganic compound layer 311 and
the etched surface of the metal oxide layer 312 were observed with
a scanning electron microscope ("S800" manufactured by Hitachi
Ltd.). As a result, no residue was left on the etched surfaces and
the etched surfaces were smooth with no steps. Further, the
inorganic compound layer 311 and the metal oxide layer 312 were
well etched in accordance with the pattern of the resist mask 314
(see Table 3-1).
EXAMPLE s 3-2 to 3-14
[0347] (a) Formation of Metal Oxide Layer and Measurement of Work
Function and Specific Resistance
[0348] (1) Formation of Metal Oxide Layer
[0349] A metal oxide layer 312 was formed on a blue plate glass
substrate 310 in the same manner as in Example 3-1 (a)(1) except
that the indium oxide-zinc oxide-cerium oxide target
([In]:[Zn]:[Ce]=80.7:14.4:4.9 atomic %) used for sputtering the
metal oxide layer 312 was changed to a target shown in Table
3-1.
[0350] As shown in Table 3-1, targets used in Examples 3-2 to 3-14
are different from each other in composition. The composition of
each of the targets used in Examples 3-2 to 3-14 is expressed in
terms of atomic % in Table 3-1. Therefore, Examples 3-2 to 3-14 are
different from each other in the composition of a target for use in
sputtering of the metal oxide layer 312. In each of Examples 3-2 to
3-14, the physical properties of the metal oxide layer 312 were
measured.
[0351] (2) Measurement of Work Function and Specific Resistance of
Metal Oxide Layer
[0352] In the same manner as in Example 3-1 (a)(2), the metal oxide
layer 312 provided on the blue plate glass substrate 310 was
cleaned by the application of X rays, and then the work function
and the specific resistance of the metal oxide layer were measured.
The measurement results are shown in Table 3-1.
[0353] (b) Manufacture of Reflective Electrode Substrate,
Measurement of Surface Resistivity, and Analysis of Etching
Characteristics
[0354] (1) Manufacture of Reflective Electrode Substrate
[0355] In each of Examples 3-2 to 3-14, an inorganic compound layer
311 and a metal oxide layer 312 were formed on a blue plate glass
substrate 310 in the same manner as in Example 3-1 (b)(1) except
that the indium oxide-zinc oxide-cerium oxide target
([In]:[Zn]:[Ce]=80.7:14.4:4.9 atomic %) used for sputtering the
metal oxide layer 312 was changed to a target with the composition
shown in Table 3-1 (see FIG. 10(3)). In this way, an electrode
layer 313 composed of the inorganic compound layer 311 and the
metal oxide layer 312 was formed on the blue plate glass substrate
310 to obtain a reflective electrode substrate 301.
[0356] (2) Measurement of Surface Resistivity
[0357] The surface resistivity of each of the reflective electrode
substrates 301 of Examples 3-2 to 3-14 was measured with a surface
resistivity meter similar to the resistivity meter used in Example
3-1. All the reflective electrode substrates 301 of Examples 3-2 to
3-14 had a surface resistivity of 1.2 .OMEGA./.quadrature..
[0358] (3) Analysis of Etching Characteristics
[0359] In each of Examples 3-2 to 3-14, a resist mask 314 was
formed on the metal oxide layer 312 of the reflective electrode
substrate 301 in the same manner as in Example 3-1 (b)(3) (see FIG.
10(4)). Then, the inorganic compound layer 311 and the metal oxide
layer 312 were subjected to etching in the same manner as in
Example 3-1(b)(3) to obtain a reflective electrode substrate 301 as
shown in FIG. 11.
[0360] The etched surface of the inorganic compound layer 311 and
the etched surface of the metal oxide layer 312 were observed with
the same scanning electron microscope as used in Example 3-1. As a
result, in all the reflective electrode substrates of Examples 3-2
to 3-14, no residue was lefton the etched surfaces, and the etched
surfaces were smooth with no steps. Further, the inorganic compound
layer 311 and the metal oxide layer 312 were well etched in
accordance with the pattern of the resist mask 314 (see Table 3-1).
TABLE-US-00006 TABLE 3-1 Composition of target Characteristics of
thin Inorganic film compound layer Metal oxide layer Work Specific
[Ag] [In] [Zn]or[Sn] Third ingredient function resistance Etched
surface Examples (atomic %) (atomic %) (atomic %) (atomic %) (eV)
(.mu..OMEGA.cm) condition 3-1 100 80.7 [Zn](14.4) [Ce](4.9) 5.92
960 Good 3-2 100 74.0 [Zn](11.5) [Pr](14.5) 5.88 860 Good 3-3 100
84.1 [Zn](14.8) [Nd](1.1) 5.61 650 Good 3-4 100 81.6 [Zn](14.7)
[Sm](3.7) 5.74 480 Good 3-5 100 82.5 [Zn](14.9) [Eu](2.6) 5.68 780
Good 3-6 100 84.3 [Zn](14.5) [Gd](1.2) 5.60 530 Good 3-7 100 79.0
[Zn](14.8) [Tb](6.7) 5.68 1950 Good 3-8 100 71.1 [Zn](15.0)
[Dy](13.9) 5.58 980 Good 3-9 100 78.2 [Zn](15.2) [Ho](6.6) 5.56 475
Good 3-10 100 78.0 [Zn](16.7) [Er](5.3) 5.48 460 Good 3-11 100 77.0
[Zn](17.7) [Tm](5.3) 5.28 420 Good 3-12 100 79.8 [Zn](16.8)
[Yb](3.4) 5.84 455 Good 3-13 100 82.5 [Zn](14.7) [Lu](2.8) 5.28 415
Good 3-14 100 85.0 [Sn](10.0) [Ce](5.0) 5.88 780 Good
EXAMPLE 3-15
[0361] (a) Manufacture of Reflective Electrode Substrate and
Analysis of Etching Characteristics
[0362] (1) Manufacture of Reflective Electrode Substrate
[0363] An inorganic compound layer 311 and a metal oxide layer 312
were formed on a blue plate glass substrate 310 in the same manner
as in Example 3-1 (b)(1) except that the Ag target (Ag: 100 atomic
%) used for sputtering the inorganic compound layer 311 was changed
to an Ag-Au-Pd target ([Ag]:[Au]:[Pd]=98.5:1.0:0.5 atomic %). In
this way, an electrode layer 313 composed of the inorganic compound
layer 311 and the metal oxide layer 312 was formed on the blue
plate glass substrate 310 to obtain a reflective electrode
substrate 301 (see FIG. 10(3)).
[0364] (2) Analysis of Etching Characteristics
[0365] A resist mask 314 was formed on the metal oxide layer 312 of
the reflective electrode substrate 301 in the same manner as in
Example 3-1 (b)(3) (see FIG. 10(4)). Then, the inorganic compound
layer 311 and the metal oxide layer 312 were subjected to etching
in the same manner as in Example 3-1 (b)(3) to obtain a reflective
electrode substrate 301 as shown in FIG. 11.
[0366] The etched surface of the inorganic compound layer 311 and
the etched surface of the metal oxide layer 312 were observed with
the same scanning electron microscope as used in Example 3-1. As a
result, no residue was left on the etched surfaces, and the etched
surfaces were smooth with no steps. Further, the inorganic compound
layer 311 and the metal oxide layer 312 were well etched in
accordance with the pattern of the resist mask 314.
EXAMPLE 3-16
[0367] (a) Manufacture of Reflective Electrode Substrate and
Analysis of Etching Characteristics
[0368] (1) Manufacture of Reflective Electrode Substrate
[0369] An inorganic compound layer 311 and a metal oxide layer 312
were formed on a blue plate glass substrate 310 in the same manner
as in Example 3-1 (b)(1) except that the Ag target (Ag: 100 atomic
%) used for sputtering the inorganic compound layer 311 was changed
to an Ag--Au--Cu target ([Ag]:[Au]:[Cu]=98.5:1.0:0.5 atomic %). In
this way, an electrode layer 313 composed of the inorganic compound
layer 311 and the metal oxide layer 312 was formed on the blue
plate glass substrate 310 to obtain a reflective electrode
substrate 301 (see FIG. 10(3)).
[0370] (2) Analysis of Etching Characteristics
[0371] A resist mask 314 was formed on the metal oxide layer 312 of
the reflective electrode substrate 301 in the same manner as in
Example 3-1 (b)(3) (see FIG. 10(4)). Then, the inorganic compound
layer 311 and the metal oxide layer 312 were subjected to etching
in the same manner as in Example 3-1 (b)(3) to obtain a reflective
electrode substrate 301 as shown in FIG. 11.
[0372] The etched surface of the inorganic compound layer 311 and
the etched surface of the metal oxide layer 312 were observed with
the same scanning electron microscope as used in Example 3-1. As a
result, no residue was left on the etched surfaces, and the etched
surfaces were smooth with no steps. Further, the inorganic compound
layer 311 and the metal oxide layer 312 were well etched in
accordance with the pattern of the resist mask 314.
EXAMPLE 3-17
[0373] (a) Manufacture of Reflective Electrode Substrate and
Analysis of Etching Characteristics
[0374] (1) Manufacture of Reflective Electrode Substrate
[0375] An inorganic compound layer 311 and a metal oxide layer 312
were formed on a blue plate glass substrate 310 in the same manner
as in Example 3-1 (b)(1) except that the Ag target (Ag: 100 atomic
%) used for sputtering the inorganic compound layer 311 was changed
to an Ag--Nd target ([Ag]:[Nd]=99.0:1.0 atomic %). In this way, an
electrode layer 313 composed of the inorganic compound layer 311
and the metal oxide layer 312 was formed on the blue plate glass
substrate 310 to obtain a reflective electrode substrate 301 (see
FIG. 10(3)).
[0376] (2) Analysis of Etching Characteristics
[0377] A resist mask 314 was formed on the metal oxide layer 312 of
the reflective electrode substrate 301 in the same manner as in
Example 3-1 (b)(3) (see FIG. 10(4)). Then, the inorganic compound
layer 311 and the metal oxide layer 312 were subjected to etching
in the same manner as in Example 3-1 (b)(3) to obtain a reflective
electrode substrate 301 as shown in FIG. 11.
[0378] The etched surface of the inorganic compound layer 311 and
the etched surface of the metal oxide layer 312 were observed with
the same scanning electron microscope as used in Example 3-1. As a
result, no residue was left on the etched surfaces, and the etched
surfaces were smooth with no steps. Further, the inorganic compound
layer 311 and the metal oxide layer 312 were well etched in
accordance with the pattern of the resist mask 314.
EXAMPLE 3-18
[0379] (a) Manufacture of Reflective Electrode Substrate and
Analysis of Etching Characteristics
[0380] (1) Manufacture of Reflective Electrode Substrate
[0381] An inorganic compound layer 311 and a metal oxide layer 312
were formed on a blue plate glass substrate 310 in the same manner
as in Example 3-1 (b)(1) except that the Ag target (Ag: 100 atomic
%) used for sputtering of the inorganic compound layer 311 was
changed to an Ag--Zr--Ni--Co target
([Ag]:[Zr]:[Ni]:[Co]=96.0:1.0:1.5:1.5atomic %). In this way, an
electrode layer 313 composed of the inorganic compound layer 311
and the metal oxide layer 312 was formed on the blue plate glass
substrate 310 to obtain a reflective electrode substrate 301 (see
FIG. 10(3)).
[0382] (2) Analysis of Etching Characteristics
[0383] A resist mask 314 was formed on the metal oxide layer 312 of
the reflective electrode substrate 301 in the same manner as in
Example 3-1 (b)(3) (see FIG. 10(4)). Then, the inorganic compound
layer 311 and the metal oxide layer 312 were subjected to etching
in the same manner as in Example 3-1 (b)(3) to obtain a reflective
electrode substrate 301 as shown in FIG. 11.
[0384] The etched surface of the inorganic compound layer 311 and
the etched surface of the metal oxide layer 312 were observed with
the same scanning electron microscope as used in Example 3-1. As a
result, no residue was left on the etched surfaces, and the etched
surfaces were smooth with no steps. Further, the inorganic compound
layer 311 and the metal oxide layer 312 were well etched in
accordance with the pattern of the resist mask 314.
COMPARATIVE EXAMPLE 3-1
[0385] (a) Formation of Metal Oxide Layer and Measurement of Work
Function and Specific Resistance
[0386] (1) Formation of Metal Oxide Layer
[0387] A metal oxide layer 312 was formed on a blue plate glass
substrate 310 in the same manner as in Example 3-1 (a)(1) except
that the indium oxide-zinc oxide-cerium oxide target
([In]:[Zn]:[Ce]=80.7:14.4:4.9 atomic %) used for sputtering the
metal oxide layer 312 was changed to an indium oxide-tin oxide
target ([In]:[Sn]=90.0:10.0 atomic %) (see Table 3-2).
[0388] (2) Measurement of Work Function and Specific Resistance of
Metal Oxide Layer
[0389] In the same manner as in Example 3-1 (a)(2), the metal oxide
layer 312 provided on the blue plate glass substrate 310 was
cleaned with X rays to measure the work function and the specific
resistance of the metal oxide layer 312. As a result, the work
function and the specific resistance of the metal oxide layer 312
were 5.12 eV and 210 .mu..OMEGA.cm, respectively (see table
3-2).
[0390] (b) Manufacture of Reflective Electrode Substrate and
Analysis of Etching Characteristics
[0391] (1) Manufacture of Reflective Electrode Substrate
[0392] An inorganic compound layer 311 and a metal oxide layer 312
were formed on a blue plate glass substrate 310 as shown in FIG.
10(3) in the same manner as in Example 3-1 (b)(1) except that the
indium oxide-zinc oxide-cerium oxide target
([In]:[Zn]:[Ce]=80.7:14.4:4.9 atomic %) used for sputtering the
metal oxide layer 312 was changed to an indium oxide-tin oxide
target ([In]:[Sn]=90.0:10.0 atomic %) (see Table 3-2). In this way,
an electrode layer 313 composed of the inorganic compound layer 311
and the metal oxide layer 312 was formed on the blue plate glass
substrate 310 to obtain a reflective electrode substrate 301 (see
FIG. 10(3)).
[0393] (2) Analysis of Etching Characteristics
[0394] A resist mask 314 was formed on the metal oxide layer 312 of
the reflective electrode substrate 301 in the same manner as in
Example 3-1 (b)(3) (see FIG. 10(4)). Then, the inorganic compound
layer 311 and the metal oxide layer 312 were subjected to etching
in the same manner as in Example 3-1 (b)(3) to obtain a reflective
electrode substrate 301 as shown in FIG. 11.
[0395] Next, the metal oxide layer 312 was subjected to etching
with an aqueous oxalic acid solution (3.5 wt %) in the same manner
as in Example 3-1 (b)(3), but the metal oxide layer was not
dissolved (see Table 3-2). TABLE-US-00007 TABLE 3-2 Composition of
target Characteristics of thin Inorganic Metal oxide layer film
compound layer Third Work Specific Comparative [Ag] [In] [Zn]r[Sn]
ingredient function resistance Etched surface Example (atomic %)
(atomic %) (atomic %) (atomic %) (eV) (.mu..OMEGA.cm) condition 3-1
100 90.0 [Sn](10.0) -- 5.12 210 The metal oxide layer could not be
etched.
[0396] As described above, according to the manufacturing method of
Comparative Example 3-1, it is difficult to carry out etching
without producing a step at the boundary between the metal oxide
layer and the inorganic compound layer. Therefore, it can be
considered that it is also difficult to manufacture a reflective
electrode substrate having a low specific resistance and a high
work function by the manufacturing method according to Comparative
Example 3-1. It is to be noted that all of the electrode layers of
Examples 3-1 to 3-18 had a high reflectivity.
[0397] (Summary of the Third Embodiment)
[0398] As described above, the reflective electrode substrate
according to the third embodiment has a low specific resistance and
a high work function because the inorganic compound layer contains
at least Ag and the metal oxide layer contains at least indium
oxide and a lanthanoid group oxide. Further, according to the
manufacturing method of the present invention, the metal oxide
layer is etched with an etchant containing oxalic acid and the
inorganic compound layer is etched with an etchant containing
phosphoric acid, nitric acid, and acetic acid. By subjecting the
metal oxide layer and the inorganic compound layer to etching in
such a manner, it is possible to manufacture a reflective electrode
substrate having substantially no step at the boundary between the
metal oxide layer and the inorganic compound layer and having
little residue on the etched surface.
* * * * *